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Full text of "Byte Magazine Volume 04 Number 09 - Homebrewing"

SEPTEMBER 1979 Volume 4, Number 9 $2.00 in 



.0 in Canada 




the small systems journal 

^ A MCGRAW-HILL PUBLICATION 






If you have a problem that can be solved by a computer— we have a systems solution. 

* Two central processors with maximum RAM capacities of 56K and 384 K bytes 

* Three types of disk drives with capacities of 175K, 1 .2M and 16M bytes 

* Two dot matrix printers with 80 and 132 line capacity 

A Selectric typewriter interface and a daisy wheel printer 

Match these to your exact need, add one or more of our intelligent terminals and put together 
a system from one source with guaranteed compatibility in both software and hardware. 

Southwest Technical Products systems give you unmatched power, speed and versatility. They 
are packaged in custom designed woodgrain finished cabinets. Factory service and support on 
the entire system and local service is available in many cities. 




SOUTHWEST TECHNICAL PRODUCTS CORPORATION 

219 W. RHAPSODY 

SAN ANTONIO, TEXAS 78216 (512) 344-0241 

Circle 356 on inquiry card. 




Low-cost hard disk computers 

are here 

11 megabytes of hard disk and 64 kilobytes of fast RAM in a 

Z80A computer for under $10K. Two floppy drives, too. 

Naturally, it's from Cromemco. 



It's a reality. In Cromemco's new 
Model Z-2H you get all of the above 
and even more. With Cromemco you 
get it all. 

In this new Model Z-2H you get 
not only a large-storage Winchester 
hard disk drive but also two floppy 
disk drives. In the hard disk drive you 
get unprecedented storage capacity 
at this price — 11 megabytes unfor- 
matted. 

You get speed — both in the 4 MHz 
Z80A microprocessor and in the fast 
64K RAM which has a chip access 
time of only 150 nanoseconds. You 
get speed in the computer minimum 
instruction execution time of 1 micro- 
second. You get speed in the hard 
disk transfer rate of 5.6 megabits/sec. 

EXPANDABILITY 

You get expandability, too. The 
high-speed RAM can be expanded to 
512 kilobytes if you wish. 

And the computer has a full 12-slot 
card cage you can use for additional 
RAM and interface cards. 

BROADEST SOFTWARE SUPPORT 

With the Z-2H you also get the 
broadest software support in the 



microcomputer field. Software Cro- 
memco is known for. Software like 
this: 

• Extended BASIC 

• FORTRAN IV 

• RATFOR (RATional FORtran) 

• COBOL 

• Z80 Macro Assembler 

• Word Processing System 

• Data Base Management 

with more coming all the time. 

SMALL, RUGGED, RELIABLE 

With all its features the new Z-2H, 
including its hard disk drive, is still 
housed in just one small cabinet. 




Included in that cabinet, too, is 
Cromemco ruggedness and reliability. 
Cromemco is time-proved. Our 
equipment is a survey winner for 
reliability. Of course, there's Cro- 
memco's all-metal cabinet. Rugged, 
solid. And, there's the heavy-duty 
power supply (30A @ 8V, 15A @ 
+ 18 V, and 15A @ -18V) for cir- 
cuitry you'll sooner or later want to 
plug into those free card slots. 

CALL NOW 

With its high performance and low 
price you KNOW this new Z-2H is 
going to be a smash. Look into it 
right now. Contact your Cromemco 
computer store and get our sales 
literature. Find out when you can 
see it. Many dealers will be showing 
the Z-2H soon — and you'll want to 
be there when they do. 



ra 



Hard disk drive at lower left can be inter- 
changed just by sliding out and disconnecting 
plug. Seven free card slots are available. 
Z-2H includes printer interface card. 



Cromemco 



PRESENT CROMEMCO USERS 

We've kept you in mind, too. Ask 
about the new Model HDD Disk 
Drive which can combine with your 
present Cromemco computer to give 
you up to 22 megabytes of disk 
storage. 



Circle 80 on inquiry card. 



•^^^J 280 BERNARDO AVE., MOUNTAIN VIEW, CA 94040 

^^* Tomorrow's computers now 



(415)964-7400 



BYTE September 1979 



Latched 
Outputs 



4 MHz 
Crystal Clock 



On Card 

Voltage 

Regulation 



Parallel 
I/O Port #1 

\ 



Parallel 
I/O Port #2 

/ 



Parallel 
I/O Port #3 

\ 



RS-232 or 
Current Loop 
I/O Port #4 




8KROM 
Capacity 



IK RAM 



Standard Bus 



for System 
Expandability 



Programmable 
Baud Rate 
UARTwith 

Interval Timers 



4 MHz Z-80A 



Completely Buffered 
Bus Interface 



The single card computer 

with the features 
that help you in real life 






COMPLETE COMPUTER 

In this advanced card you get a pro- 
fessional quality computer that meets 
today's engineering needs. And it's one 
that's complete. It lets you be up and 
running fast. All you need is a power 
supply and your ROM software. 

The computer itself is super. Fast 
4 MHz operation. Capacity for 8K bytes 
of ROM (uses 2716 PROMs which can 
be programmed by our new 32K BYTE- 
SAVER® PROM card). There's also 1K of 
on-board static RAM. Further, you get 
straightforward interfacing through an 
RS-232 serial interface with ultra-fast 
speed of up to 76,800 baud — software 
programmable. 

Other features include 24 bits of bi- 
directional parallel I/O and five on- 
board programmable timers. 

Add to that vectored interrupts. 



ENORMOUS EXPANDABILITY 

Besides all these features the Cro- 
memco single card computer gives you 
enormous expandability if you ever need 
it. And it's easy to expand. First, you 
can expand with the new Cromemco 
32K BYTESAVER PROM card mentioned 
above. Then there's Cromemco's broad 
line of S100-bus-compatible memory 
and I/O interface cards. Cards with fea- 
tures such as relay interface, analog 
interface, graphics interface, opto- 
isolator input, and A/D and D/A con- 
version. RAM and ROM cards, too. 




Card Cage 32K BYTESAVER PROM card 



EASY TO USE 

Another convenience that makes the 
Model SCC computer easy to use is our 
Z-80 monitor and 3K Control BASIC (in 
two ROMs). With this optional software 
you're ready to go. The monitor gives 
you 12 commands. The BASIC, with 36 
commands/functions, will directly ac- 
cess I/O ports and memory locations — 
and call machine language subroutines. 

Finally, to simplify things to the ulti- 
mate, we even have convenient card 
cages. Rugged card cages. They hold 
cards firmly. No jiggling out of sockets. 

AVAILABLE NOW/ LOW PRICE 

The Cromemco Model SCC is avail- 
able now at a low price of only $450 
factory assembled ($395 kit). 

So act today. Get this high-capability 
computer working for you right away. 



G 



Cromemco 

incorporated 
Specialists in computers and peripherals 
280 BERNARDO AVE., MOUNTAIN VIEW, CA 94040 



(415) 964-7400 



2 BYTE September 1979 



Circle 80 on inquiry card. 




In The Cue we 



BITI September 1979 
Volume 4, Number 9 



Foreground 



10 
20 
34 
70 
96 
118 
130 

62 

84 

160 

182 

196 



JOYSTICK INTERFACES by Steve Ciarcia 
An interface for every purpose 

INTRODUCTION TO MULTIPROGRAMMING by Mark Dahmke 
Some basic concepts 

INTERFACE A CHESSBOARD TO YOUR KIM-1 by Jeff Teeters 
Play chess with a computer as easily as with a human opponent 

A LOW-SPEED ANALOG-TO-DIGITAL CONVERTER by Richard C Hallgren 
Perform real-time data analysis 

THE NATURE OF ROBOTS, Part 4 by William T Powers 
A simple, human experiment 

INEXPENSIVE, OPTICAL PAPER-TAPE READER by Brian A Harron 
A manual paper-tape reader with no moving parts 

A MODEL OF THE BRAIN FOR ROBOT CONTROL, Part 4 by James Albus 
Decision-making procedures 




Background 



page JO 



SOME MUSINGS ON HARDWARE DESIGN by Clayton Ellis 
Simple design techniques 

SOLDERING TECHNIQUES by William Trimmer 
A picture essay 

HANDY PULSER by Bob Chrisp 
A simple, circuit-debugging tool 

THE AMSAT-GOLEM-80 by Joe Kasser 

A modular and inexpensive S-100 computer system 

ADD SOME CONTROL TO YOUR COMPUTER by Ken Barbier 
Let your computer influence the outside world 




Nucleus 



Editorial: The Rationale of 

Yet Another Homebrew System 6 
Programming Quickies 58,126 
Unclassified Ads 61 
BYTE's Bits 80 
Technical Forum 82 
Clubs and Newsletters 92 
BYTE News 115 



Book Reviews 122, 152 
Letters 150 
Languages Forum 164 
Event Queue 176 
What's New? 214 
Reader Service 256 
BOMB 256 



page 34 



Cover Art: Fantasy on Homebrewing by Robert Tinney. 




BYTE is published monthly by BYTE Publications Inc. 70 Main St, Peterborough NH 03458, a wholly-owned subsidiary of McGraw-Hill, Inc. Address all mail except subscriptions 
to above address: phone (603) 924-7217. Address subscriptions, change of address, USPS Form 3579, and fulfillment questions to BYTE Subscriptions, PO Box 590, Martinsville 
NJ 08836. Second class postage paid at Peterborough NH 03458 and at additional mailing offices— USPS Publication No. 102410 (ISSN 0360-5280). Subscriptions are $18 for one 
year, $32 for two years, and $46 for three years in the USA and its possessions. In Canada and Mexico, $20 for one year, $36 for two years, $52 for three years. $32 for one year air 
delivery to Europe. $32 surface delivery elsewhere. Air delivery to selected areas at additional rates upon request. Single copy price is $2 in the USA and its possessions, $2.40 in 
Canada and Mexico, $3.50 in Europe, and $4 elsewhere. Foreign subscriptions and sales should be remitted in United States funds drawn on a US bank. Printed in United States of 
America. 

Address all editorial correspondence to the editor at the above address. Unacceptable manuscripts will be returned if accompanied by sufficient first class postage. Not 
responsible for lost manuscripts or photos. Opinions expressed by the authors are not necessarily those of BYTE. Entire contents copyright © 1979 by BYTE Publications Inc. All 
rights reserved. 

BYTE's is available in microform from University Microfilms International. 300 N Zeeb Rd, Dept PR. Ann Arbor Ml 48106 USA or 18 Bedford Row, Dept PR, London WC1R 4EJ 
ENGLAND. 



Subscription WATS Line: (800) 258-5485 



Office hours: Mon-Thur 8:30 AM - 4:30 PM 
Friday 8:30 AM - Noon 



September 1979 © BYTE Publications Inc 3 





About the Cover 

On this issue's cover, Robert 
Tinney has created a "fantasy on 
homebrewing. " In the middle of 
a sylvan glade, we see the form 
of a computer being sculpted by 
some homebrewer. A couple of 
humanoid forest denizens look 
on with wonder, perhaps hoping 
to get a glimpse of our home- 
brewer on his return to the work- 
place. 



Building a joystick in- 
terface for your computer 
system adds a new 
physical input dimension. 
There are as many dif- 
ferent ways to interface a 
joystick as there are ap- 
plications. Steve Ciarcia 
discusses several widely 
varying ways to design 
Joystick Interfaces. 
Page 10 

The idea of having a 
microcomputer work in a 
multiprogramming en- 
vironment is becoming a 
reality. Already there are 
several multiprogram- 
ming systems on the 
market. Mark Dahmke 
provides an Introduction 
to Multiprogramming so 
we can understand how 
these systems operate. 
Page 20 



If you enjoy playing 
chess against your com- 
puter, but dislike typing 
in the moves in abstract 
notation, you will be in- 
terested in a method of 
allowing the computer to 
detect moves made on a 
real chessboard. Jeff 
Teeters devised such a 
method and now tells us 
how he did it in Interface 
a Chessboard to Your 
KIM-1. 

Page 34 



Some Musings On 
Hardware Design by 

Clayton Ellis provides 
readers with background 
information on picking 
integrated circuits and 
using them in homebrew 
work. 

Page 62 



Although there are 
many applications where 
a high-speed analog-to- 
digital converter is 
necessary, many conver- 
sion applications can 
make do with a slower 
conversion. Richard C 
Hallgren has built A 
Low-Speed Analog-to- 
Digital Converter for the 
Apple II which he uses as 
a real-time data analyzer. 
Page 70 



When constructing 
electronic equipment, it is 
imperative that good 
Soldering Techniques are 
developed. William Trim- 
mer presents a photo 
essay of good soldering 
practices and several ex- 
amples of unwanted 
techniques. 

Page 84 



William T Powers 
brings his discussion of 
The Nature of Robots to 
a close by applying the 
previously-discussed 
techniques and theories in 
a simple experiment with 
a human subject. 
Page 96 



The search for the in- 
expensive paper-tape 
reader continues as Brian 



A Harron describes an 
Inexpensive, Optical 
Paper-Tape Reader. 

Page 118 



James Albus considers 
the mechanisms of choice 
in his closing article 
about A Model of the 
Brain for Robot 
Control. 

Page 130 



A Handy Pulser can 

prove to be very useful 
when testing a digital cir- 
cuit. Bob Chrisp shares 
with us his version of a 
useful pulse generator. 
Page 160 



In The AMSAT- 
GOLEM-80, Joe Kasser 
shows how your com- 
puter club (or any other 
group of experimenters) 
can economically build 
an S-100 microcomputer. 
The system is modular 
and expandable. 
Page 182 



Performing simple con- 
trol functions with your 
computer can be easy. 
Ken Barbier describes 
how to Add Some Con- 
trol to Your Computer. 
Page 196 



Publishers 

Virginia Londoner 
Gordon R Williamson 
Associate Publisher 
John E Hayes 
Assistant 
Jill E Calllhan 

Editorial Director 

Carl T Helmers Jr 
Executive Editor 
Christopher P Morgan 
Editor In Chief 
Raymond G A Cote 
Senior Editor 
Blaise W Llffick 
Editor 

Richard S Shuford 
Assistant Editors 
Kent Richard 
Bob Braisled 
Editorial Assistants 
Gale Britton 
Faith Ferry 
New Products Editor 
Clubs, Newsletters 
Laura A Hanson 
Drafting 
Jon Swanson 



Production Director 

Nancy Estle 
Production Editors 

David William Hayward 

Ann Graves 

Faith Hanson 

Warren Williamson 

Robin M Moss 

Anthony J Lockwood 

Art Director 

Ellen Bingham 

Production Art 

Wai Chiu LI 

Christine Dixon 

Holly Carmen LaBosslere 

Deborah Porter 

Typographers 

Cheryl A Hurd 
Debe L Wheeler 
Sherry McCarthy 
Kathy Becker 
Photostat Technician 
Tully Londner 



Advertising Director 

Patricia E Burgess 
Assistants 
Ruth M Walsh 
Marion Gagnon 
Janet Ames 
Eileen Kindl 
Adv/Prod Coordinator 
Thomas Harvey 
Advertising Billing 
Noreen Bardsley 
Don Bardsley 

Circulation Manager 

Gregory Spltzfaden 
Assistants 
Pamela R Heaslip 
Agnes E Perry 
Melanle Bertoni 
Barbara Ellis 
Dealer Sales 
Ginnie F Boudrieau 
Anne M Baldwin 
Receptionist 
Jacqueline Earnshaw 



National Advertising 
Sales Representatives: 

Hajar Associates Inc 

East 

280 Hillside Av 

Needham Heights MA 02194 

(617) 444-3946 

521 Fifth Av 

New York NY 10017 

(212) 682-5844 

Midwest 

664 N Michigan Av 

Suite 1010 

Chicago IL 60611 

(312)337-8008 

West, Southwest 

1000 Elwell Ct 

Suite 227 

Palo Alto CA 94303 

(415) 964-0706/(714) 540-3554 

Traffic Department 

Mark Sandagata 
Thomas Yanni 

Comptroller 

Kevin Maguire 
Assistant 

Mary E Fluhr 



Officers of McGraw-Hill 
Publications Company: Gordon 
L. Jones, President; Group Vice 
Presidents: Daniel A. McMillan, 
James E. Boddorf; Senior Vice 
Presidents: Russell F. Anderson; 
Ralph R. Schulz, Editorial; Vice 
Presidents: James E. Hackett, 
Controller; Thomas H. King, 
Manufacturing; Robert L. 
Leyburn, Circulation; John W. 
Patten, Sales; Edward E. 
Schlrmer, International. 

Officers of the Corporation: 
Harold W. McGraw Jr., President, 
Chief Executive Officer and 
Chairman of the Board; Robert F. 
Landes, Senior Vice President 
and Secretary; Ralph J. Webb, 
Treasurer. 



September 1979 © BYTE Publications Inc 



***** 



I've seen Lanier, Vydec, 

Xerox, Olivetti, and Wang. 

I've chosen WORDSMITH 

from MICRO DIVERSIONS. 



Congressman Charlie Rose 

Chairman, Policy Group 

on Information and 

Computers 



LOORDsrrjftb 



TEXT EDITOR 



Yes, I'd like to learn more about Wordsmith.™ Send me your information packet. 
Name. 



Company 

Address. 

City 



State 



Zip 



Micro Diversions, Inc. 
8455-D Tyco Road, 
Vienna, Virginia 22180 
(703) 827-0888 

BYTE September 1979 5 



Look for 

in personal 

computer systems 

made by these 

companies. 



Editorial 



Altos Computer Systems 

2378-B Walsh Avenue 
Santa Clara. CA 95050 

Apple Computer 

10260 Bandley Dr. 
Cupertino, CA 95014 

Digital Microsystems Inc. 

(Formerly Digital Systems) 
4448 Piedmont Ave. 
Oakland, CA 94611 

Imsai Mfg. Corporation 

14860 Wicks Blvd. 

San Leandro, CA 94577 

Industrial Micro Systems 

633 West Katella, Suite L 
Orange, CA 92667 

North Star Computer 

2547 9th Street 
Berkeley. CA 94710 

Percom Data 

318 Barnes 
Garland, TX 75042 

Polymorphic Systems 

460 Ward Dr. 

Santa Barbara, CA 93111 

Problem Solver Systems 

20834 Lassen Street 
Chatsworth, CA 91311 

Processor Applications Limited 

2801 E. Valley View Avenue 
WestCovina, CA91792 

SD Sales 

3401 W. Kingsley 
Garland, TX 75040 

Smoke Signal Broadcasting 

6304 Yucca 
Hollywood, CA 90028 

Technico Inc. 

9130 Red Branch Road 
Columbia, MD 21045 

Texas Electronic Instruments 

5636 Etheridge 
Houston, TX 77087 

Thinker Toys 

1201 10th Street 
Berkeley, CA 94710 

Vista Computer Company 

2807 Oregon Court 
Torrance, CA 90503 



Shugart 

6 September 1979 © BYTE Publications lnc 



The Rationale of 
Yet Another Homebrew System 



by Carl Helmers 

In this issue of BYTE, we are placing a special emphasis on the homebrewing 
of computers: the craft of assembling the hardware and software of a system 
from standard components in nonstandard ways. This month's editorial pro- 
vides a continuation of notes begun in July on the design and assembly of my 
new homebrew 6809 system. In this editorial, we complete the final details of 
the physical layout and power supplies of the system, as well as the overall 
design of the system. We shall also begin a discussion of the actual processor 
card. Future installments in this series on homebrew, general purpose, com- 
puter hardware will record details of the system beyond this article's goal of 
defining a backplane bus structure. 

As noted earlier ("Editorial," June 1979 BYTE, page 6), the intent of this 
exercise is to develop a specialized controller node for a loosely coupled system 
of processors involved with musical applications. The multiple processors ini- 
tially contemplated were a Pascal-oriented, large personal computer and an 
ALF products model AD-8 music synthesizer with its 6502 used for house- 
keeping. In addition to this coordinating task, the 6809 would provide a cen- 
tral point for the connection of keyboards, displays and other hardware re- 
quired by musical applications. 

But ideas change and evolve. Since the 1st installments were written, plans 
have become slightly more grandiose with my recent acquisition of a New 
England Digital "Synclavier" music synthesizer and its associated Able/60 
minicomputer. Located in Norwich VT, New England Digital is a combined 
spin-off of the music and electrical engineering departments of Dartmouth 
College across the Connecticut river in NH. The computer for the music syn- 
thesizer employs the XPL language as its high-level user interaction. The New 
England Digital version of XPL is augmented by a floating-point data type. 
With the exception of an adaptation of UCSD Pascal, which is expected to be 
available soon, all systems software is written in XPL, including what is 
described as a 3-pass optimizing XPL compiler. 

[XPL is the language described in the book A Compiler Generator, by 
McKeeman, Wortman, et al, published circa 1968. The commonly used 
microcomputer language PL/M, 1st designed and implemented by Gary 
Kildall, is very similar to XPL in syntax and semantics. XPL is a simple subset 
of PL/I, with data types restricted to character and integer forms.] 

At this point, I now have a need for multiple processor communications 
beyond the level of 1 large machine (a Western Digital P-engine) driving a 
smart peripheral through a serial communications link. The smart peripheral 
will still handle specialized details like the parallel interface to the older syn- 
thesizer and the eventual interface to an electronically controlled player piano. 
See photo notes on pages 8 and 9, text continued on page 202 



My Shugart 

followed me li 






* 



u 




\ 






« 



IX 



i 




"After working all day with the computer at 
work, it's a kick to get down to Basic at home. And 
one thing that makes it more fun is my Shugart 
minifloppy™- We use Shugart drives at work, so 
when I Pought my own system I made sure it had a 
minifloppy drive, 

"Why? Shugart invented the minifloppy. The 
guys who designed our system at work tell me that 
Shugart is the leader in floppy design and has 
more drives in use than any other manufacturer. If 
Shugart drives are reliable enough for hard-working 
business computers, they've got to be a good 
value for my home system. 

"When I'm working on my programs late at 
night, I can't wait for cassette storage. My 
minifloppy gives me fast random access and data 



transfer. The little minidiskettes store plenty of 
data and file easily too. 

"I made the right decision when I bought a 
system with the minifloppy. When you lay out your 
own hard-earned cash, you want reliability and 
performance. Do what I did. Get a system with the 
minifloppy." 

If it isn't Shugart, 
it isn't minifloppy. 

*A Shugart 

435 Oakmead Parkway. Sunnyvale, California 94086 



See opposite page for list of manufacturers featuring Shugart's minifloppy in their systems. 

TM minifloppy is a registered trademark ot Shugart Associates 



BYTE September 1979 



Hardware Basis... 

These photographs depict some fur 
details of the physical hardware of the 
new homebrew 6809 computer system. As 
noted earlier, Vector Electronic Co com- 
ponents were used for the assembly of a 
backplane. Photographs 1 through 5 show 
various aspects of the new design's 
packaging. 

Photo 1: The new computer system's final 
physical mounting basis is a mahogony 
box with guide blocks for the backplane 
assembly. Power supplies are located 
underneath the box. Power for the com- 
puter and accessories will be controlled by 
the standard, household wall switch 
mounted on the side of the box. Power 
connections to the backplane power buses 
will pass through a hole underneath the 
backplane in this photo. The hole pro- 
vides an exit path for the flow of hot air 
from the power supplies. 

Individual boards of the system plug 
into the backplane from the top as shown 
here. The backplane assembly slides into 
the grooves of the 2 guide blocks. These 
blocks are bolted to the top of the box 
using Vi-20 machine-screws and threaded 
inserts. The grooves for the backplane 
board were cut l/16th of an inch wide 
with a router and edge guide. The wood- 
shop tools required to fabricate this case 
included a table saw, electric hand drill, 
drill press, router, belt sander, sabre saw, 
and the usual collection of hand tools. 

Photo 2: The power supply modules are 
attached to 2 wooden brackets which are 
screwed into the main box by means of 
Vi-20 machine-screw threaded inserts. 
The power supply modules are mounted 
on the brackets using §8-32 threaded in- 
serts. Ordinary brass finish door stops 
serve as legs to keep the assembly off the 
table top, thus allowing natural convec- 
tion to cool the power supply modules. 

No attempt is made to calculate heating 
factors. The inverted cup shape of the box 
seems like an excellent trap for heat, 
however, the large hole beneath the 
backplane assembly at the top of the box 
provides a relatively low-impedance 
outlet for the heated air from below. If the 
temperatures observed under load are 
excessive, then a fix will be necessary. In a 
commercial or industrial engineering 
situation where production of a product is 
contemplated, this "patch up after pro- 
blems" strategy is not the recommended 
practice due to the possibilities of costly 
errors, but for one of a kind products in a 
noncommercial and highly experimental 
context, it is certainly acceptable and can 
economize on time. 

Photo 3: (a) Brass machine-screw inserts 
to provide metal to wood fastening in the 



(1) 



(2) 



(3a) 




8 September 1979 © BYTE Publications Inc 




(5a) 



(5b) 






assembly of the computer housing. These 
particular parts were purchased from the 
Brookstone Co Peterborough NH. 

(b) When inserting the machine-screw 
fasteners into hardwood, better results 
were obtained when the hole drilled in the 
wood was l/64th of an inch larger than 
the recommended size in the instructions. 
A short section of the machine-screw to be 
used, together with a hex nut, provide a 
tool for driving the insert as shown in this 
picture. When using the §8-32 inserts in 
hardwood, a slightly larger hole than sug- 
gested in the instructions is a necessity. 
Unless the extra clearance is given, the 
torque on the §8-32 bolt used in driving 
the insert will cause the insert to twist 
apart after 1 or 2 uses. 

Photo 4: The backplane is the first and the 
most tiresome wiring involved with 



assembly of a small computer. Its defini 
Hon is provided by the simple instruc- 
tions: 

FOR each free socket, pin BY NUMBER 
OF each socket, 

CONNECT that pin to the same pin 
of the next socket in the backplane! 

The backplane assembly loas described 
in the notes of the July 1979 BYTE, page 
194. This photo shows the finished 
backplane after all wiring and installation 
of bypass capacitors has been completed. 

Photo 5: The wiring of the backplane, as 
well as the rest of this computer, was done 
with the Vector Electronic Co's "slit-N- 
xorap" technique. An electric eraser was 
used to motorize the connections, with an 
adapter custom-made on a small lathe. It is 



recommended that motorized wiring be 
employed with the "slit-N-wrap" tech- 
nique. In previous experimental elec- 
tronics built with this technique, relia- 
bility problems were encountered with 
manual termination of the wires to wire- 
wrap socket posts. Motorized wrapping 
with this tool provides a uniform and 
higher force for stripping the insulation 
off the wire. 

At (a) is the adapter: a hollow tube 
made from 2 junk box spacers, a §10-32 
bolt with a hole drilled through it, a brass 
union between the 2 spacers, and a large 
brass adapter to which a §10-32 nut is 
soldered. (This latter kludge is what hap- 
pens when one makes an adapter on a 
Sunday afternoon and a §10-32 tap is not 
available!) At (b) the completed adapter is 
mounted in the Bruning Electric Eraser in 
a typical use situation. 

September 1979 © BYTE Publications Inc 9 






Gispcis's Circuit Bella* 



Copyright © 1979 by Steven 
A Ciarcia. All rights reserved. 



Joystick Interfaces 



Steve Ciarcia 

POB 582 

Glastonbury CT 06033 




Photo 1: A typical joystick with 4 potentiometers. 



The thought that often comes to 
mind when the word joystick is men- 
tioned to a computer enthusiast is of a 
spacewar-type game. A photon 
torpedo is fired from an opponent's 
starship, and the thruster joystick is 
deftly moved to reposition the craft 
out of its path. All of this occurs 
without having to take your eyes off 
the screen. Eye/hand coordination is 
almost "instinctive." With a glance to 
the upper right of the video screen, 
the joystick is tilted to the upper-right 
corner of its 360° range. This moves 
the spacecraft toward that coor- 
dinate. Reverse thrust is accomplish- 
ed by moving the joystick in the op- 
posite direction, as though you are 
pulling back on the throttle of a real 



craft. Such is the general experience 
with joysticks. However, the poten- 
tial use of these devices greatly ex- 
ceeds that of game playing. 

A joystick, for those people who 
are unfamiliar with one, is shown in 
photo 1. It is an electromechanical 
device with resistance outputs pro- 
portional to the X,Y displacement of 
a central ball and lever. Photo 2 
illustrates the mechanical connections 
to the potentiometers. 

When the stick is positioned in the 
center of its axes, the X and Y poten- 
tiometers show resistances in the 
center of their ranges. When the stick 
is tilted to the upper right, both 
potentiometers are at their full- 
resistance limit, while the opposite 




Photo 2: Note how moving the stick 
moves the gimbal arrangement, which in 
turn changes the settings of the poten- 
tiometers. 



(lowest resistance) is true when in the 
lower-left position. The outputs of 
the 2 potentiometers accurately track, 
as if on an X,Y coordinate axis, the 
position of the joystick. It should be 
noted that while it takes only 2 poten- 
tiometers to define 2-dimensional 
travel, most joysticks are manufac- 
tured with 4 potentiometers. This is a 
remnant of the days when joysticks 
were connected directly to the 4 
deflection-plates of a cathode ray 
tube (video screen). 

It is one thing to consider inter- 
facing a joystick to a computer, and 
quite another to do it. A joystick is a 
mechanical X,Y positioning device. 
Even with proportional output resis- 
tances, an input interface must be 
designed to convert position from an 
analog to a digital representation 
which can be used by the computer. 
A further consideration is the resolu- 
tion, or percent, of full-scale travel 
per bit sensitivity. Is the application 
so gross that center and full-scale are 
the only points of interest, as in a 



10 September 1979 © BYTE Publications Inc 



ILL TO' 



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1 Tarbell Floppy Disk Inter- 
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1 CP/M Disk Operating Sys- 
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1 Tarbell BASIC. 
All Cables and Connectors. 

> Complete User Documenta- 
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> Fully factory assembled and 
tested. 

1 ; $1888.00 










950 DOVLEN PLACE • SUITE B • CARSON, CALIFORNIA 90746 
(213) 538-4251 • (21 3) 538-2254 



Circle 360 on inquiry card. 



BYTE September 1979 11 



2 JOYSTICK POTENTIOMETERS 




J 1 !~7 

^IN4728 ^, F / 

T 3.9V ^ / 

rh m „ 1/ iok 



470 



nsv 
i 



C>B3 



0> B2 



Obi 



O B0 



TO 4 LEAST 
SIGNIFICANT 
BITS OF 
INPUT PORT I 



ICI 

LM339 



IOM 
■VW- 



Number Type 
IC1 LM339 

IC2 LM339 




O 87 



OB6 



OB5 



C>B4 



TO 4 MOST 
SIGNIFICANT 
BITS OF 
INPUT PORT I 



+ 5 V GND 

3 12 

3 12 



"R«= APPROXIMATELY IOOOHMS 



Figure 1: Low-resolution static interface. This interface is for 1 2-potentiometer joystick. For 4-potentiometer joysticks, build a second 
circuit like this one, and interface it to another input port. Note that if the comparator does not trigger at full-scale setting, a small 
resistor may have to be added at Rx (marked with asterisk). 



game control, or is the application 
one which requires fine control, such 
as a cursor-positioning device in a 
high-resolution graphics system? 

All joystick interfaces are not 
created equal. There is a trade-off 
between hardware and software. The 
lower the resolution, the fewer the 
parts. The higher the resolution, the 
greater the electrical complexity or 
the software interaction with the in- 
terface. It is also important to 
recognize that computer systems 
which operate only in a high-level 
language like BASIC cannot use an 
interface design that requires an 
assembly language subroutine as an 
integral component. In such instances 
only a static interface can be used. 

Included in this presentation are 4 
interface designs which should cover 
most requirements, as well as 
demonstrate the considerable dif- 
ferences between them. The 4 types 
are: 

• low-resolution static 



• high-resolution fully static 
hardware 

• software-driven pulse-width 
modulated 

• high-resolution analog-to-digital 

Low-Resolution Static Interface 

First of all, static simply means that 
the interface hardware determines the 
potentiometer position value and pre- 
sents it in constant, parallel digital 
form to the computer. When the 
interface is attached to any parallel 
input port, this joystick value can be 
read with a single INPUT command 
in BASIC. As far as the computer is 
concerned, the value is fully static, 
and the computer reads whatever 
data is there when the INPUT is ex- 
ecuted. The interface hardware has 
the responsibility of asynchronously 
updating the digital value as the stick 
is moved. 

Often the joystick is simply used to 
indicate relative direction and 
magnitude. In a wheelchair, for in- 
stance, full linear control of speed 



and direction would require rather 
expensive drive electronics. Most 
chairs use simple relay contacts and 
provide 2 or 3 selectable speeds. A 
joystick control built for this applica- 
tion would not have to have a resolu- 
tion of 8 bits, but could, in fact, suf- 
fice with 2. Figure 1 shows a low- 
resolution static output joystick inter- 
face suitable for use in this 
application. 

Each potentiometer is connected as 
a voltage divider between a reference 
voltage source of 3.9 V and ground. 
The voltage output of each poten- 
tiometer is, in turn, fed to a 2-bit, 
parallel analog-to-digital converter. 
This type of converter uses 4 com- 
parators set for 25%, 50%, 75%, and 
100% of full scale. If a voltage, when 
applied, is less than 0.975 V, all com- 
parator outputs will be at V. At 1.0 
V, corresponding to the joystick be- 
ing moved 25% of full scale, the least 
significant bit (LSB) of the converter 
will be a logic 1, while the other bits 
are low. Similarly, at full input all 



12 September 1979 © BYTE Publications Inc 





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BYTE September 1979 13 



comparators will be triggered, and 
bits thru 3 will be logical Is. 

Additional encoding logic can be 
added to produce a true 2-bit 
representation from the 4 compara- 
tors, but it is just as easy for a com- 
puter to interpret it directly. With a 



4-bit connection as shown, used in a 
BASIC program, 25% of full scale 
would be 1 decimal, 50% of full scale 
would be 3 decimal, 75% of full scale 
would be 7 decimal, and full scale 
would be 15 decimal. It should be 
easy to trigger any action by a coin- 



cidence with these values. The real 
significance of this method is that the 
potentiometer position is presented 
statically to the computer and re- 
quires no other interaction. This 
makes it ideal for direct use with 
BASIC. 



5V 
A 



1 



50K 



;o.i/iF 



3 4 



■<Z3 CLOCK 



Al A2 

Cext Q 

ICI 

74121 

35ms 

r ext/c EX t 



o 



8-BIT Ri POSITION 



BO Bl B2 B3 



B4 B5 B6 B7 







IC6 
7404 



7486 



7400 






O.I/uF 



3 LOAD 



7400 



12 



II 







10 



Q A B Q c Qd 

L0CK 2 '7 C 4 9 95 

A B C D 



6 CLEAR 



CLOCK O- 



HTv J COUNT 
IC5a fc> 



+ 5V 
A 



V R 2 __ 
4 50K ^pO.I M F 



-<Z2 CLOCK 



IC6 
7404 



13 



12 



II 







Q A Q B Q c Q D 
A B C D 



A B C D 

INPUT B | C7 

INPUT A 7493 

RO(I) R0(2) 



A B C D 

INPUT B , C8 

INPUT A 7493 

RO(l) R0(2) 



Al A2 



Cext Q 

IC2 

74121 

35ms 

R EXT /C EXT 



8-BIT R-> POSITION 



30 Bl B2 B3 



B4 B5 B6 B7 







IC6 
7404 

E* 8 



u. I3 

47ft 



7400 



1 
I 



10 i ^ 

13. . \ g LOAD 

"TTJJ IC3b)o^ f-^l _J/ > ~ 



O.I/iF 



7400 



13 



II 











Q A Qb Qc Od 

LOCK 2 £| g 

A B C D 



II CLEAR 



CLOCK 0>- 



6 COUNT 



IC6 
7404 



12 



13 



12 



II 



10 



Qa Ob Qc Qd 
lock 2 !£« B 

A B C D 



A B C D 



INPUT B 



ICI I 



INPUTA ? 493 

ROU) RO(2) 



L^i 



A B C D 



INPUT B 



I C 12 



INPUTA ? 493 

RO(l) R0(2) 



14 September 1979 © BYTE Publications Inc 



High-Resolution Static Interface 

It is quite possible that 2 bits of 
resolution is not enough for your 
application, but direct compatibility 
with a slow, high-level language is 
still a requirement. Expanding the 
parallel comparator method will 
work in theory, but you must realize 
that a 4-bit analog-to-digital con- 
verter uses 15 comparators, and an 
8-bit, parallel analog-to-digital con- 
verter needs 255 comparators! So 
much for that method. 

Realizing that the output of the 
joystick is a variable resistance, we 
can use this to advantage. This resis- 
tance can set the time constant of a 



Number 


Type 


+ 5 V 


GND 


IC1 


74121 


14 


7 


IC2 


74121 


14 


7 


IC3 


7486 


14 


7 


IC4 


7400 


14 


7 


IC5 


7400 


14 


7 


IC6 


7404 


14 


7 


IC7 


7493 


5 


10 


ice 


7493 


5 


10 


IC9 


7495 


14 


7 


IC10 


7495 


14 


7 


IC11 


7493 


5 


10 


IC12 


7493 


5 


10 


IC13 


7495 


14 


7 


IC14 


7495 


14 


7 


IC15 


NE555 


8 


1 



5V 

A 



y FREQUENCY 

*? ADJUSTMENT 

IOK 



ICI5 
NE555 



RESET VCC 
DISCHARGE 

OUTPUT 
THRESHOLD 
TRIGGER 
GROUND BYPASS 



iO.ljiF 



rh 



O.OI/iF 

9h- 



J 



Figure 2: High-resolution, static interface. 
Each potentiometer in the joystick con- 
trols the pulse width of a one-shot. The 
pulse width can vary from 35 ms at full- 
scale to 100 /as at 0. If a joystick with 4 
potentiometers is used, a duplicate circuit 
may be constructed for the 3rd and 4th 
potentiometers. 



function which has a pulse width pro- 
portional to joystick position. Figure 
2 illustrates an interface design which 
uses this technique. 

The 2 joystick potentiometers Rl 
and R2 control the pulse width of a 
one-shot (monostable multivi- 
brator). The one-shot has a pulse 
width of 35 ms when the poten- 
tiometer is at 50 k ohm full scale and 
something less than 100 lis at 0% of 
full scale. A 7.5 kHz clock signal 
asynchronously triggers the one-shots. 
When the one-shot fires, its duration 
is proportional to the joystick posi- 
tion and will vary from approxi- 
mately to 35 ms. Using midscale 
pulse width of 17 ms as an example, 
the circuit timing is as in figure 3. 

On the leading edge of the one-shot 
signal, a clear pulse is generated 
through an edge detector configured 
7486 device. The clear pulse resets the 
2 7493s which form an 8-bit counter. 
Once cleared, the counters start 
counting clock pulses for the duration 
of the one-shot's period. On its trail- 
ing edge, a load pulse is generated 
which loads this 8-bit count into an 
8-bit storage register. The computer is 
connected to read this 8-bit value 
through a parallel input port. Suc- 
cessive clearing and counting opera- 
tions update the register every 35 ms 
or so (worst case). The clock rate is 
7.5 kHz which has a period of 133 /xs. 
If the one-she has a pulse width of 17 
ms, then 127 clock pulses would be 



CLOCK 



ONE SHOT Q 



jil. 



gated to the counter. Of a total possi- 
ble 255 counts, 127 would represent 
50% of full scale. 

Software-Driven Interfaces 

So far I have discussed only static 
interfaces. If the computer used with 
the joystick has sufficient speed and 
excess computing time available, then 
it is reasonable to use the computer to 
directly determine the one-shot 
period. 

Figure 4 shows a circuit which 
directly connects to the computer bus 
and demonstrates this technique. The 
circuit as shown is wired for I/O (in- 
put/output) port decimal 255 or 
hexadecimal FF. The 4 joystick poten- 
tiometers are used as the timing 
resistors on 4 NE555-type one-shots. 
When an OUT 0, FF is executed in 
assembly language, it triggers all 4 
one-shots. To keep track of the pulse 
widths, a 74125 3-state driver gates 
the one-shot outputs onto the data 
bus during an IN FF instruction. By 
looping through this program a 
number of times and keeping track of 
the logic levels of the 4 one-shots, the 
computer can accurately determine 
joystick position in terms of loop 
counts of instruction times. Listing 1 
is a program which does this for 1 
potentiometer. 

High-Resolution Analog-to-Digital 

While all methods are in some way 
analog-to-digital converters, the last 



7.5 KHz 



CLEAR 



LOAD 



COUNT 



TO 35 mSEC 



20/iSEC 



20 M SEC 



TO 255 PULSES 



Figure 3: Timing diagram for interface of figure 2. The driving clock signal is 7.5 kHz. 
The one-shot can be triggered for periods of to 35 ms, depending upon the position of 
the joystick. When a reading is to be taken, the counters are cleared. Counts are made 
until the one-shot signal drops, and then a load signal is sent to the interface. At this 
point the counter is read to determine the position of the joystick. 

September 1979 © BYTE Publications Inc 15 





MVI 


B 


clear B 




OUT 


FF,0 


trigger one-shots 


AGAIN 


INR 


B 


increment B register 




IN 


FF 


read potentiometers 




ANA 


01 


isolate bit 




JNZ 


AGAIN 


continue as long as one-shot is high 




HLT 




value is in B register 



Listing 1: A typical assembly language program for using the joystick interface of figure 
4. After the one-shots are triggered, the program loops and checks the status of bit 0. 
When this bit is set, the conversion value is in register B. This program assumes that 
there is only 1 value being checked, and it is being input through bit 0. 



method is in fact an 8-bit absolute- 
analog-to-digital converter, typical of 
the type used in computerized meas- 
urement applications. ICl is an 8-bit 



Number 


Type 


+ 5 V 


GND 


IC1 


NE556 


14 


7 


IC2 


NE556 


14 


7 


IC3 


7430 


14 


7 


IC4 


7400 


14 


7 


IC5 


74125 


14 


7 



digital-to-analog converter that pro- 
duces an output voltage proportional 
to a digital input applied to pins 5 
thru 12. For a complete explanation 
of this device, I refer you to a pre- 
vious " Ciarcia's Circuit Cellar" arti- 
cle, "Control the World" (September 
1977 BYTE, page 30). This article also 
outlines calibration and test pro- 
cedures. 



The 3 basic sections are a 
computer-controlled voltage source 
(ICs 1 and 2), an analog-input 
multiplexer (IC3) which selects an in- 
dividual joystick potentiometer by a 
2-bit address code, and a comparator 
(IC4) which compares these voltages. 
In operation, the digital-to-analog 
converter is first set to V out (hexa- 
decimal 00 digital input to it) and 1 
potentiometer is selected through the 
multiplexer. If V0 from the digital-to- 
analog converter is less than V in from 
the potentiometer, the output will be 
logic 0. Next, the digital-to-analog 
converter input setting is incre- 
mented, and the comparator output is 
checked again. 

Eventually an input count will be 
reached which will exceed V,„. The 
comparator output will then be a 
logic 1. The digital-to-analog con- 
verter input count is now the value of 
the voltage V,„. The worst case re- 
quires 256 iterations using this 



R| THRU R 4 
ARE JOYSTICK 
POTENTIOMETERS 



+ 5V 




ao rz> 



TO 

COMPUTER j 
CONTROL 
BUS 



I/O r^. 
WRITE I 



'^E> 



READ I — >^ 



IC4 
7400 



I 


■ 50K 


>2.2K 

2 


Ida 

OUTPUT 
THRESHOLD 

DISCHARGE 

CONTROL 
TRIGGER 


5 


ICl 
NE556 


2 






3 








1 




^O.I^F 

7 








/TN 0.01/iF 




n 


1* 








HZ> D o 



I* R 2 
-> 50K 



OUTPUT 
THRESHOLD 



DISCHARGE 

CONTROL 
TRIGGER 




"1 



0.01/tF 



FR3 
SOK 






O.ljiF 



OUTPUT 
THRESHOLD 

DISCHARGE 

CONTROL 
TRIGGER 



ICE 
NE556 




^-pO.OI^F 



k R 4 
/S 50K 



OUTPUT 
THRESHOLD 

DISCHARGE 

CONTROL 
TRIGGER 



~zy* 






O.OI/iF 



HZ>°I 



TO 

COMPUTER 

DATA 

BUS 



■£>»! 




-O D 3 



Figure 4: Software-driven interface. If the computer can directly read the input from the joystick interface, the hardware required can 
be greatly simplified. When hexadecimal FF is output to port 0, all 4 one-shots are triggered. The pulse width is then determined by a 
program running through a short loop looking at the logic levels of the 4 one-shots. Listing 1 shows a typical program for this 
application. 



16 September 1979 ft) BYTE Publications Inc 




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Circle 216 on inquiry card. 



BYTE September 1979 17 



Number 


Type 


+5 VGND 


+ 15 V 


+ 15 V 


IC1 


MC1408-L8 


13 


2 


3 




IC2 


LM301A 






4 


7 


IC3 


CD4051 




4 




8 


IC4 


LM301A 






4 


7 



DIGITAL-TO-ANALOG CONVERTER 



+ I5V 



FROM COMPUTER 
OUTPUT PORT I 



B 7 O 
B 6 O- 
B5 O" 

b 4 o- 

B 3 O" 

B 2 O- 

B| O- 

B O 



MSB 5 



10 



LSB 12 



ICI 
MCI408LS 



lo 

-Vref 



RANGE 
CONTROL 



COMPEN 



i 33pF 



-I5V 



FROM COMPUTER 
OUTPUT PORT 2 



B| O" 
B O- 



10 



IC3 
CD405I 



OUT 
INI 



IN2 



IN3 



IN4 
INH C 



W* 



I.8K 



FULL 
SCALE 
ADJUST 
2K 

— y& — 



? 



?IN823A 
6 " 



OFFSET 
ADJUST 
5K 

— y& — 



2.2K 
-WA<- 



I^F 



/77 



2.7K 
_VW— 



l M F 



rn 



47pF 



4.7K 
— W\/- 



:i50pF 




LM30IA 



; 3.3K 



DIGITAL TO ANALOG CONVERTER 
SET FOR TO 2.56V 



JOYSTICK MULTIPLEX 



V REF = 2.56V 



FIRST PAIR OF 
POTENTIOMETERS ! 




SECOND PAIR OF 
POTENTIOMETERS 




R 4 
IOOK 



Figure 5: High-resolution analog-to-digital conversion. This hardware-oriented device 
multiplexes 4 voltage inputs (from the joystick potentiometers) and has the capability of 
handling 4 more voltages. 



method. A better technique is suc- 
cessive approximation where the 
computer progresses through a 
binary search to "zero in" on the final 
value. A full explanation of suc- 
cessive approximation is delineated in 
my article entitled "Talk to Me: Add 
a Voice to Your Computer for $35" 
(June 1978 BYTE, page 142). 



With the digital-to-analog con- 
verter set for a full-scale value of 2.56 
V, each count is equivalent to 10 mV. 
Only 4 channels of the CD4051 are 
used for the joysticks, leaving 
another 4 channels as auxiliary inputs 
from external sources. Thus it is 
possible for this interface to serve a 
dual role because of its high accuracy 



COMPARATOR 



-O VqUT 



. 33pF 




TO COMPUTER 
INPUT PORT 1 

C>Bo 



LM30IA 



and resolution relative to the other 
methods. 

You should now realize that both 
the design and construction of a 
joystick interface are influenced by 
many factors. It is not unusual to find 
one manufacturer charging $50 for a 
joystick, while another charges $200. 
Resolution, accuracy, and software 
interaction are the prime considera- 
tions. Where static inputs are re- 
quired, the hardware will necessarily 
be more complicated. Resolution and 
accuracy ultimately determine the 
complexity of the interface. 

For simple spacewar-type games, 
the circuit of figure 1 should suffice. 
For more demanding applications 
such as cursor control in a high- 
resolution graphics system, figure 5 
may be the optimum choice. Be 
careful when buying joystick inter- 
faces. Make sure that they mate with 
your program requirements and your 
system's abilities. 

Next month's "Circuit Cellar" 
feature will discuss a stand-alone, 
light-emitting diode display board. ■ 



18 September 1979 © BYTE Publications Inc 



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BYTE September 1979 19 



Introduction to 
Multiprogramming 



Mark Dahmke 

8312 Selleck 

600 N 15th St 

Lincoln NE 68508 



Multiprogramming has usually 
been considered out of reach of the 
average personal computer experi- 
menter using a small or medium scale 
computer. Actually, anyone with a 
processor above the level of an 8008 
can operate a multiprogram or 
multiuser system. The original pur- 
pose of multiprogramming was to 
allow more than 1 user to take advan- 
tage of a computer simultaneously. 
This increased the productivity of the 
machine by allowing programs to run 
while other programs were awaiting 
user input, access to a disk, etc. 

This may seem to conflict with the 
advantages inherent in micro- 
processor based systems (single user 
systems and low cost). However, 
there are many instances where the 
ability to run more than 1 program at 
a time may be advantageous. Note 
that the statement "more than 1 pro- 
gram may run at a time" does not 
mean simultaneous execution. That is 
the definition of multiprocessing 
(more than 1 processor on the bus), 
not multiprogramming. 

To describe multiprogramming 
more effectively, I shall refer to a 
more well-known function in com- 
puters: real-time interrupts. Suppose 
we are using a microcomputer to 
manage the environment in a small 
office building. Normally we want to 
continually poll (scan) the sensors 
that are distributed throughout the 
building and adjust heating, cooling 
and lights on the basis of temperature 
and time of day. Let us say that 



during normal operation, someone in 
the building wants to change the 
temperature of an office. 

One way to do this is to have a 
video terminal and keyboard attach- 
ed to the system that generates an in- 
terrupt when a keyboard request is 
made. Upon receiving the interrupt, 
the computer saves the status of the 
current program and enters or trans- 
fers control to the keyboard read 
routine. As soon as the user has made 
the desired change, the system loads 
the old status information and returns 
to the original program. This same in- 
terrupt technique could be used to 
design a time shared system that 
would allow several terminals to be 
hooked up to a processor. Each ter- 
minal would generate an interrupt, 
and whichever program was active 
would be put in a wait state. This 
arrangement only works well for a 
few terminals, though. You can ima- 
gine what would happen if everyone 
happened to press a key at the same 
time. 

Figure 1 shows timing comparisons 
of several modes of operation already 
discussed. In figure la 2 independent 
processors are shown, each doing 
something different and neither in- 
terfering with the other. This is 
known as multiprocessing. The pro- 
cessors may or may not be sharing 
I/0(input/output) terminals or 
memory. 

In figure lb 2 processors are shown 
in a master-slave arrangement. 
Perhaps the slave processor performs 



floating point arithmetic or some 
complex I/O function. The master 
processor can give the slave processor 
commands via an interrupt and con- 
tinue other processing until the slave 
informs it that it has finished the 
desired operation. 

Figure lc shows a single processor 
with an interrupt being applied. The 
processor temporarily gives control 
to the routine specified by the inter- 
rupt hardware and begins executing 
it. When complete, it returns control 
to the main program. Figure Id shows 
the multiterminal timeshare system. 
Usually the interrupt hardware con- 
tains provisions for daisy chaining or 
prioritizing the interrupts as they 
come in. Thus, if terminal 6 applies 
an interrupt and the processor is busy 
with terminal 7, terminal 6 is not 
allowed to interrupt the processor 
until terminal 7 is finished. 

Using multiprogramming is like 
using real-time interrupts. A multi- 
programmed system uses interrupts, 
but in a more efficient way. Imagine a 
simple 2 program situation. Suppose 
program A is running and no other 



About the Author 

Mark Dahmke is currently employed by the 
University of Nebraska Computer Network as 
a programmer/analyst in the Academic Com- 
puting Services section. He is also a senior 
computer science major. At home, Morlc owns 
an 8080 based system with 32 K bytes of 
memory and dual iCOM floppy disk drives. 
His work involves graphics, electronics, 
writing, systems programming and speech syn- 
thesis. 



20 September 1979 © BYTE Publications Inc 



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programs have been started. Then a 
user initiates (loads) another program 
called B. How will program B gain 
control of the system so that it might 
start to execute? 

The process of passing control 
from one program to the next is 
usually handled by an operating 
system module referred to as an inter- 
rupt call routine. Normally, to save 
the programmer the trouble of 
making sure that this routine gets 
called at regular intervals, the routine 
is usually imbedded in many of the 
I/O driver routines or other standard 
utility subroutines on a system. Note 
that this technique will in no way 
upset any of the flags or registers of 
the routine it is called from. 

This interrupt call program will: 

1. Determine if any other programs 
are waiting to execute. 



2. If so, save all registers and flags on 
the stack and save the address of 
the current program's stack 
pointer in a special table in 
memory. 

3. Load the new program's stack 
pointer from the table, pop all 
registers and flags off the stack. 

4. Return to the new program. 

Loading the new stack pointer 
raises some interesting questions. If 
program B has not yet begun, how 
could its registers have been pushed 
onto its stack? Figure 2 shows the 
stacks of both programs as they 
would be at each step in the previous- 
ly described interrupt call routine. 
Part of the job of the routine that in- 
itialized program B is to set up a 
dummy stack and stack pointer such 
that the program counter address on 
the top of the stack contains the entry 



point of program B. Thus, when the 
interrupt call routine reaches step 4, it 
will execute a return instruction, then 
pop the entry point address off the 
stack and begin executing program B. 
When the interrupt routine is called 
again, it will see that program A is 
waiting and will save all of program 
B's registers and flags, swap stack 
pointers and return to program A at 
the point where it was first inter- 
rupted. 

All this activity will take place 
every time the interrupt routine is 
called, but if one of the programs gets 
caught in an infinite loop, the inter- 
rupt call routine may not get called. 
The simplest way to avoid this kind 
of problem is to add some hardware 
to provide external timed interrupts. 
As shown in figure 3, the interrupt 
timer is set to provide an interrupt 
every 10 ms. A reset line is provided 



PROCESSOR 



PROGRAM A 



PROGRAM A 



PROGRAM A 



PROGRAM A 



PROGRAM A 



(a) 



PROCESSOR 2 



PROGRAM B 10 



PROGRAM B 



PROGRAM B 



10 PROGRAM B 



PROGRAM B 



PROGRAM 8 



(b) 



(c) 



(d) 



PROGRAM A 


PROGRAM A 
CONTINUES 
OTHER WORK 


PROGRAM A / 


SLAVE PROGRAM INITIATED 
SLAVE 1 




SLAVE SENDS READY SIGNAL 


INACTIVE OR 
DOING OTHER WORK 


PROGRAM A 
SLAVE PROGRAM 


INACTIVE OR DOING OTHER WORK / 


/ EXTERNAL INTERRUPT 

/ OCCURS 


PROGRAM A 


INTERRUPT ROUTINE 


PROGRAM A RESUMED / 




OPERATING TERMINAL 
SYSTEM SERVICED 


OPERATING 
SYSTEM 


TERMINAL 7 
SERVICED 


TERMINAL 6 
SERVICED 


TERMINAL 7 
COMPLETED 


TERMINAL 6 
COMPLETED 


OPERATING/ 
SYSTEM / 


TIME 



Figure 1; Timing diagrams for 4 different system organizations. Figure la is a multiprocessing example using 2 independent pro- 
cessors. Figure lb is a multiprocessing example using 2 processors connected in a master-slave configuration. Figure lc is a single pro- 
cessor with 1 level of interrupt. Figure Id is a single processor with 8 levels of interrupts. Each of the 8 levels is activated by 1 of 8 ter- 
minals. 



22 September 1979 © BYTE Publications In 



STACK A 



STACK POINTER A 





' 


11 ) 


PROGRAM COUNTER 
(HIGH) 


— 


PROGRAM COUNTER 
(LOW) 



AFTER INTERRUPT CALL 
STACK B 







(3) 


PROGRAM COUNTER 

(HIGH) 




PROGRAM COUNTER 
(LOW) 




ALL REGISTERS 




FLAGS 





STACK POINTER B 



(STACK POINTER 
SAVE AREA ) 







(2) 


PROGRAM COUNTER 
(HIGH) 




PROGRAM COUNTER 
(LOW) 




ALL REGISTERS 






FLAGS 












STACK POINTER A 


(STACK POINTER 
SAVE LOCATION) 



STACK B 



(4) 



STACK POINTER B- 



PROGRAM COUNTER 
(HIGH) 



PROGRAM COUNTER 
(LOW) 



Figure 2: Arrangement of all stacks and stack pointers at each interval of an interrupt call routine. 



in the event that the interrupt routine 
is manually called (through the soft- 
ware method). The timer may be 
reset to give the program its full 10 
ms. A disable line is provided to 
allow the user to turn off the timer for 
special applications (software timing) 
in which the processor must not be in- 
terrupted. 

Figure 4 shows our previous exam- 
ple of figure 1, but with the extra 
hardware generated interrupts added. 
In figure 4a some software interrupts 
are mixed in with the hardware inter- 
rupts. The timer is reset after each call 
to the interrupt routine. Figure 4b is 
the same except that the timer is not 
reset after each call. 

A Complete System 

There are limitless ways to go 
about developing a computer system 
that will be easy to use. A look at the 
current market shows this to be true, 
perhaps even to a greater extent on 
the small systems level. I will not at- 
tempt to describe all possible varia- 
tions available on a multiprogram- 



ming system, but I will try to give as The following are essential: 
generalized a view as possible. 

First, we must consider what is 1. Some form of operating system 
necessary to make a useful system. that allows simplified user com- 



4> 



£~ 



470ft 

4 — va — 



s 



(THREE STATE) 



> 



C^ 



-[ ~> TO INTERRUPT 
LINE OF 
PROCESSOR 



D FLIP-FLOP 



o 



Figure 3: Simple hardware interrupt timer set for 10 ms intervals. 



September 1979 © BYTE Publications Inc 23 



TIMER RESET 
BY SOFTWARE 



TIMER RESET 
BY SOFTWARE 



TIMER RESET 
BY SOFTWARE 



(a) 



PROGRAM A 



PROGRAM B 



PROGRAM A 



PROGRAM B 



PROGRAM A 



PROGRAM B 



PROGRAM A 



PROGRAM B 



TIMER 
INTERRUPT 



TIMER 
INTERRUPT 



10 

INTERRUPT 

CALL 



TIMER 
NOT RESET 



TIMER 
INTERRUPT 



TIMER 
INTERRUPT 



10 

INTERRUPT 

CALL 



10 

INTERRUPT 

CALL 



TIMER 

NOT RESET 



(b) 



PROGRAM A 



PROGRAM B 



PROGRAM A 



PROGRAM A 



PROGRAM B 



PROGRAM B 



PROGRAM A 



TIMER 
INTERRUPT 



TIMER 
INTERRUPT 



10 

INTERRUPT 

CALL 

TIMER 

INTERRUPT 



TIMER 
INTERRUPT 



10 

INTERRUPT 

CALL 

TIMER 
INTERRUPT 



TIMER 
INTERRUPT 



10 

INTERRUPT 

CALL 



Figure 4: Interrupt timing example of figure 1 reviewed with the addition of a hardware timer. The timer may be used in 2 ways: The 
example in figure 4a resets the timer on each interrupt call. This allows each program to receive its full 10 ms time slot. The example in 
figure 4b does not reset the timer. Therefore, a hardware interrupt occurs every 10 ms. 



munications (ie: BASIC, DOS, 
CPM). 

2. Convenient mass storage I/O 
(cassette or disk). 

3. Sufficient memory to handle all 
programs. 

Another consideration might be the 
internal architecture of the processor, 
but that is another level of problem. 

Figure 5 shows the memory layout 
of a typical multiprogramming 
system. To maintain a simple system, 
I have combined the operating system 



with the timesharing routines that 
support all terminals (video displays, 
keyboards and teletypewriters). This 
means that each time the operating 
system gains control (through an 
interrupt call or timer interrupt), it 
will complete its own activity and 
then transfer control to the time- 
sharing program for the remainder of 
the time slot. If the operating system 
is given highest priority, the response 
times of the terminals should not suf- 
fer. The operation of the timeshare 
program can be treated as a multi- 



BOOTSTRAP 
LOADER 


INTERRUPT 
ROUTINE 


TIME- 
SHARING 
SUPPORT 
PROGRAM 


ALL I/O 
ROUTINES 


OPERATING 
SYSTEM (0) 


STACK 


USER PROGRAM 1 


STACK 1 




USER PROGRAM 2 


STACK 2 
















~~ — ^ 



Figure 5: System geography of a typical multiprogramming system with space for the 
operating system and 2 other programs. 



program system in miniature, where 
each terminal is given a time slot, or it 
may be designed to simply scan the 
terminals, choosing a new terminal 
each time it is given control. 

Controlling I/O 

Many programmers have dis- 
covered the convenience of vectoring 
all I/O through 1 subroutine; this 
simplifies programming greatly and 
makes system changes much easier. 
Typically, 1 subroutine will accept an 
operand (if necessary) and an 
operator function code passed from 
the main program and will decide 
which I/O function to perform. In 
my hypothetical computer, this ap- 
proach will be used. Note that in 
some large computer systems, the 
I/O driver programs can only be ac- 
cessed by executing a special kind of 
interrupt call that informs the 
operating system that the user's pro- 
gram desires to perform some kind of 
input or output operation. The oper- 
ating system then takes charge, per- 
forms the I/O for the program in 
question, and returns pointers telling 
where the input data was stored in 
memory or that the requested output 
function has been completed. 

This type of I/O handling is neces- 
sary because the I/O controllers are 
extremely complex and are capable of 
performing an entire I/O operation 



24 



September 1979 © BYTE Publications Inc 



Circle 9 on inquiry card.- 




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^w How to buy -*- 
11 personal compute 



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Visit your local computer store 

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What to look for 

Your neighborhood computer store has several 
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without processor intervention. In 
fact, it would be very inefficient to 
make the processor of a large system 
perform these menial tasks when it 
could be working on more important 
programs. In microcomputer systems 
we are not normally concerned with 
the optimization of I/O functions and 
it does not really hurt performance to 
have the processor perform most of 
the I/O. Consequently, the I/O 
driver routines in the system I am 
describing will not be considered as 
part of the operating system. They 
are just utility subroutines that may 
be called by the user's program. 

Defining the Necessary Tables 

With only 2 programs very few, if 
any tables are needed to tell the inter- 
rupt routine which program was ac- 
tive at the instant the system was in- 
terrupted and which program is next 
in line. But imagine a system capable 
of supporting 10 or more programs: 
some form of priority scheduling will 
be needed, as well as a table to hold 
all of the stack pointers of the inactive 
programs. 



To handle the list of programs 
(herein referred to as tasks), we must 
define a task control table that keeps 
track of a number of pointers and 
descriptors. First, each entry will 
begin with the task number that uni- 
quely defines each task. Next, we will 
include the priority of the task on an 
arbitrary scale of to 10. It will then 
get the processor before a task of 
lower priority (10 is highest). If 2 
tasks have the same priority, the first 
one in line in the task control table 
will get control. The task control 
table must also keep track of the last 
value of the stack of each task and 
whether or not the task may be inter- 
rupted (in the case of critical timing 
loops). 

Another important status byte that 
must be kept is the current activity 
indicator. This byte contains the task 
number of the currently active task. 
Now let us assume that we have 3 dif- 
ferent tasks running and all have been 
initialized (stored in the task control 
table). The first task has a task 
number of and a priority of 10. 
Generally the operating system is 



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given the task number designation. 
Since the operating system and 
timeshare program (user terminals) 
are considered one big program in 
this example, task is also the 
designation of the timeshare system. 
Task 1 is a program that one of the 
users submitted (initiated) from a ter- 
minal; it has a priority of 10. Task 2 
was also loaded and initiated by a 
user through the timeshare terminals, 
and it has a priority of 10. 

Imagine that the timeshare pro- 
gram calls the I/O driver program to 
write a character out to a terminal. 
Since there could be many terminals 
connected to the system, how does 
the program know which one to write 
to? It would be very inefficient to 
have different routines for each 
device, but the only way that a pro- 
gram could tell the I/O driver which 
specific display to write to is for the 
calling program to know the physical 
address of that terminal. Passing the 
actual address of the device ruins the 
neatness of the I/O routine, though. 
It is more convenient to specify the 
function to be performed (1 = write 
to video display; 2 = read keyboard; 
3 = write to cassette; 4 = read 
cassette). 

The solution is to have another en- 
try in the task control table called a 
communications control block 
pointer that points to the location of 
the communications control block for 
the particular task. Since each task is 
given its own block, the user may 
define his or her own functions and 
addresses. Thus each program may 
have its own video display, key- 
board, cassette interface and disk. 
The communications control block 
contains a list of function numbers, 
the address of the I/O port or 
memory mapped port, and the ad- 
dress of the I/O subroutine that will 
perform the operation. Figure 6 
shows the arrangement of all tables. 

Starting and Stopping 

To initialize a new task, the user 
adds entries to the appropriate tables 
through a console command and 
causes a dummy stack and stack 
pointer to be created. To stop a task, 
the last thing done in the task is to call 
a subroutine that would remove its 
task control table entry. This is 
equivalent to a CALL EXIT in FOR- 
TRAN found on many larger 
systems. 



26 September 1979 © BYTE Publications Inc 



Circle 220 on inquiry card. 



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BYTE SeptemoeP 



CURRENT 
ACTIVITY 
INDICATOR 




COMMUNICATIONS 

CONTROL 

BLOCK 



(ONE FOR EACH TASK 
CONTROL TABLE ENTRY) 



I/O 

FUNCTION 

CODE 



I/O ROUTINE 
ADDRESS TO 
HANDLE THIS 
FUNCTION 



I/O PORT OR 
MEMORY MAPPED 
ADDRESS 
ASSIGNED TO 
TASK # n 



END OF TABLE MARKER 
(HEXADECIMAL FF) 



COMMUNICATIONS 

CONTROL 

BLOCK 
















L — 





COMMUNICATIONS 

CONTROL 

BLOCK 
















L- 







Figure 6: Control table organization. The current activity indicator contains the task number of the active task. The task control table 
contains the task number, task priority, last value of stack pointer, interrupt status flag (1 for yes, for no interrupts), and the 
pointer to the task's communications control block. The communications control block contains the I/O (input/output) function 
code, address of I/O driver routine associated with the function code, and the I/O port or memory mapped address assigned to the 
task for the particular function. One entry is provided for each function code used in the task. The owner of the task may add entries 
to the communications control block for specialized I/O driver requirements. 



Example 

The easiest way to show how all 
tables and pointers affect each other 
and the system is to observe them 
during a short period of machine ac- 
tivity. As we begin, task (the 
operating system and timeshare 
routines) has control, and a timer 
interrupt is occurring. There are 2 
other tasks in memory: task 1 has 
priority 5 and task 2 has priority 4. 

First, as the interrupt routine is 
entered it saves all registers and flags 
of task on stack and saves the task 
stack pointer in the task task con- 
trol table entry (see figure 7). Next, it 
scans the task control table for the 
task of next highest priority, moves 
the new task number (task 1) to the 



current activity indicator, moves the 
task 1 stack pointer from the task 
control table to the processor's stack 
pointer, pops all of task l's registers 
and flags off of stack 1, and executes 
a return, which has the effect of pop- 
ping the program counter and jump- 
ing to that address. 

Task 1, while executing, en- 
counters a call to the I/O driver 
routine with a request for a keyboard 
input (see figure 8). When the I/O 
driver routine is entered, it scans the 
task control table to find the com- 
munication control block pointer 
entry for task 1 (the routine deter- 
mines which task called it by looking 
at the current activity indicator), then 
scans the communication control 



block for the function number entry 
corresponding to the one passed by 
the main program. Even though the 
computer may have 5 or more key- 
boards attached to it, the port address 
found in the communication control 
block gives it the address of the 
keyboard assigned to task 1. 

Since the keyboard read routine is 
a common one, the address referred 
to in the communication control 
block points to a subroutine located 
within the operating system area. 
Note that if the user had need for 
some special I/O subroutine, he 
could locate it in his own memory 
area and put the address in his com- 
munication control block as another 
function code. 



28 September 1979 © BYTE Publications Inc 



Returning to the example, the 
keyboard read subroutine is called 
from the I/O driver, reads the 
keyboard port assigned to task 1, and 
returns to the I/O driver with the 
ASCII code. The I/O driver returns 
to the main program with the ASCII 
code in a register or memory loca- 
tion. In figure 9 the next timer inter- 
rupt has occurred, so control returns 
to the interrupt handler routine. 
Again, the interrupt routine saves all 
registers and flags of task 1 on stack 
1, looks at the current activity in- 
dicator to see which program was last 
active, saves the stack pointer in the 
task 1 task control table entry, scans 
the task control table for the next 
highest priority task, and finds that 
task 2 should get control. The stack 
pointer for task 2 is loaded from the 
task control table, all registers and 
flags are popped off of stack 2 and 
again a return is executed that causes 
task 2 to take control. 

In the next step (shown in figure 
10), task 2 has encountered the 
equivalent of a CALL EXIT or STOP 
command and has finished process- 
ing. This CALL EXIT calls a ter- 
minator routine which again finds out 
who called it (via the current activity 
indicator) and simply eradicates the 
task control table entry for that task. 
To keep things neat, all succeeding 
table entries are moved up 1 notch. 
Then, control is returned to the inter- 
rupt handler, which will find the next 
task in line. In this case, since no 
other tasks of lower priority are 
waiting, control is returned to the 
highest priority task 0. 

Error Handling 

On a single program system, error 
handling is something that the user 
can watch for manually. When 
several programs are running, the 
system must have routines to handle 
errors rapidly so that other programs 
will not be slowed down or 
destroyed. There are many common 
errors that are relatively easy to deal 
with. Executing an invalid op code or 
forgetting to put in the 2nd or 3rd 
byte of a multibyte op code can be 
handled through a simple system 
restart (through the interrupt handler 
routine) without losing continuity. 
But what about a program loop that 
accidentally destroys part or all of 
another user's program? On an IBM 
360, all memory blocks assigned to a 



TRANSFER OF CONTROL 
DATA OR POINTERS 




Figure 7: Task has control of the processor and has just been interrupted. The inter- 
rupt routine looks at all pointers, saves the status, and then transfers control to task 1. 



task are given a unique 4-bit protect 
key (which is the same as the task 
number) that is stored in external 
hardware. 

One approach might involve 
having 2 external 16-bit registers that 
could be loaded by the interrupt 
routine with the high and low 
memory addresses of the active task. 



Then, every time the address bus has 
a valid address on it, it is tested 
against these registers. However, 
special precautions would have to be 
taken in those cases in which a utility 
in low memory (I/O driver routine 
etc) is called, or when memory map- 
ped I/O ports outside these address 
limits are used. 



■ TRANSFER OF CONTROL 
: DATA OR POINTERS 



BOOTSTRAP 

LOADER 




„--- 


INTERRUPT 
ROUTINE 




1 I/O DRIVER 

/ ! * i 




— "■" 




'/ 1/ 1 / | 

/KBD/IN Jf' ) \ 

\0 1 \ 






^ -* 


/ 




CURRENT 
ACTIVITY 
INDICATOR 


s / 

/ / 

S S . 


/ / * 








TASK 
CONTROL 

TABLE 








COMMUNICATIONS 
CONTROL BLOCK . 


STACK 1 


TASK 1 






COMMUNICATIONS 
CONTROL BLOCK 1 






STACK 1 




















__ ^^ 



Figure 8: Task 1 has requested keyboard input from its assigned keyboard. When the 
input is completed, the I/O (input/output) driver returns control to task 1. 



September 1979 © BYTE Publications Inc 29 



= TRANSFER OF CONTROL 
■ DATA OR POINTERS 




Figure 9: Task 1 has been interrupted and turns control over to the interrupt routine. 
Control is then passed to task 2. 



■■ TRANSFER OF CONTROL 



. — = DATA OR POINTERS 



BOOTSTRAP 
LOADER 








INTERRUPT 
ROUTINE 














1 






CURRENT 
ACTIVITY 
INDICATOR 










N / 


TASK 
CONTROL 

TABLE 






^ 






COMMUNICATIONS 
CONTROL BLOCK 




TERMINATOR 




STACK 




/ * 




TASK 1 






COMMUNICATIONS 
CONTROL BLOCK 
ONE 






STACK 1 


TASK 2 






COMMUNICATIONS 
CONTROL BLOCK 2 






STACK 2 























Resolving Allocation Conflicts 

Allocating I/O devices has been a 
problem since the early days of com- 
puters. Devices like tape drives and 
card readers (sequential devices) are 
nonshareable: only 1 program may 
use them at a time. However, disk 
drives are considered shareable, since 
the head may be positioned at ran- 
dom to gather data. The simplest 
method that can be applied to the 
system described in this article would 
be to have the initiator program 
check all communication control 
blocks to make sure that certain 
devices are not assigned more than 
once. 

I/O Software Considerations 

As mentioned earlier, I/O techni- 
ques in use on small systems leave all 
control up to the processor. If special 
timing is needed or if strobes or ready 
flags have to be checked, software is 
used instead of extra hardware, as in 
the case of larger systems. This in 
itself is good from the standpoint of 
economy, but requires that special 
care be taken when writing the driver 
and controller software. 

For example, suppose a cassette 
read routine uses a universal asyn- 
chronous receiver transmitter 
(UART) implemented in software as 
an algorithm instead of hardware. In 
a nonmultitasking system, the pro- 
gram may simply loop and time 
down between bits, but in a multitask 
system the timer interrupt would 
surely halt the activity and execute 
other programs. It may be well over 
30 ms before it can return to the 
cassette read routine. It is easy to see 
what can happen to critical timing 
loops on a system that uses any kind 
of interrupts. 

The solution? If you must do the 
critical timing in software, it is 
necessary to turn off the interrupt 
timer while in the critical loop and 
reactivate it when in noncritical parts 
of the routine. If external hardware is 
used, and internal timing is reduced 

Figure 10. Task 2 has completed its execu- 
tion and encounters a CALL EXIT. Con- 
trol is given to the terminator routine 
which performs some cleanup operations 
and removes the task 2 entry from the 
task control table, effectively destroying 
the task. Control is then given to the inter- 
rupt routine which again scans the task 
control table to find the next task awaiting 
execution. 



30 September 1979 © BYTE Publications Inc 



Circle 255 on inquiry card. 



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to noncritica] loops, the intervention 
of the multitask interrupt timer will 
not normally affect the system. If the 
interrupt timer causes an interrupt 
just before a byte is received by the 
UART but returns in time for the 
next byte to be received, the easiest 
way to assure that the cassette read 
routine does not drop a byte is to set 
the timing of the interrupt oscillator 
to at least twice as fast as the 
transmission rate of the UART. This 
greatly reduces chances of losing a 
byte. 

An alternate approach is to have 
even more hardware that forces the 
interrupt timer to timeout and return 
control to the program awaiting the 
data transfer operation when the in- 
coming data is present. A third way 
involves the use of direct memory ac- 
cess (DMA) capability, in which the 
external controller reads the UART 
and deposits the data directly into 
memory. With this approach, the 
calling program need only initialize 
the external registers and go into a 
wait state until the transfer is com- 
plete, allowing the rest of the tasks to 



execute normally. This last approach 
is used on many large systems and 
constitutes what is called a channel. 

Managing the System 

As you can see, many levels of ac- 
tivity are required to control a 
multiprogramming system properly. 
It is also apparent that some minimal 
hardware is required to prevent one 
user from obtaining exclusive control 
of the processor or writing over 
someone else's program or data. The 
use of control tables and a standard 
interrupt routine are also important 
as a way of letting the interrupt 
routines and I/O drivers know which 
task had control of the processor last. 

If the user plans to run BASIC soft- 
ware or some other kind of language 
interpreter, the safety features 
discussed earlier may be implemented 
as part of the interpreter. To run a 
lower-level operating system that 
allows the user to generate assembler 
level code will generally require the 
hardware described in this article, 
thus safeguarding the system and its 
users from accidental loss of pro- 



grams or data. In general, the use of 
timed interrupts allows for a fairly 
even distribution of processor 
activity, and depending on the cycle 
time of the host system, between 4 
and 12 tasks may be handled without 
too noticeable a delay in response 
time.H 



REFERENCES 

Abrams, Marshall D, and Stein, Philip G, 
Computer Hardware and Software, Addison- 
Wesley, Reading MA, 1973. 

• Davis, William S, Operating Systems, 
Addison-Wesley, Reading, MA, 1977. 

Martin, Donald P, Microcomputer Design, 
Martin Research Ltd, Northbrook IL, 1976. 

Signetics Data Manual, Signetics Corpora- 
tion, Sunnyvale CA, 1976. 

Struble, George W. Assembler Language 
Programming: The IBM System 360 370, se- 
cond edition, Addison-Wesley, Reading MA, 
1975. 

Tanenbaum, Andrew S, Structured Com- 
puter Organization, Prentice-Hall, Englewood 
Cliffs NJ, 1976. 




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Interface a Chessboard 
to Your KIM-1 



Jeff Teeters 

1720 Coolidge Ct 

Eau Claire WI 54701 



Chess is a fascinating game. Com- 
puter chess is especially fascinating 
because the complex analysis which 
determines each move is performed 
by a machine instead of a human. 
Computer chess offers an excellent 
way to demonstrate the power and 
versatility of personal computers. 

Most computer chess systems are 
unable to "see" a chessboard. A 



human playing against a computer 
will usually set up a chessboard 
beside the computer, and the moves 
will be communicated to and from 
the machine through the use of a 
keyboard and a display in some type 
of abstract notation. 

Keyboard entry of moves is unde- 
sirable. It is inconvenient, error 
prone, and inelegant. The abstract 




Photo 1: Two pawns, a White Knight, and a loose rivet are shown on top of the elec- 
tronic chessboard. One row of 8 light emitting diodes (LEDs) is placed along the left side 
of the board, and another row is placed along the bottom of the board as seen by the 
human player. Two LEDs are lit to indicate a single square, using an X, Y axis system. A 
single large hole is drilled in the center of each square to accept entrance of the rivet 
which is glued to the bottom of each chessman. The rivet completes an electrical circuit 
between 2 pieces of wire that run from smaller holes through the large central hole. This 
switching arrangement allows the computer to detect the presence or absence of a piece 
at each square of the board. In this prototype, an additional set of 3 wires is seen in each 
square; these wires remain from an earlier, unsuccessful switching attempt. 



notation promotes errors and makes 
play difficult for people who do not 
know the notation system. Further- 
more, errors may not be detected un- 
til many intervening moves have 
occurred. 

An ideal chess-playing system 
would contain a digital television 
camera to observe the board and a 
mechanical arm to move the pieces. 
[A mechanical arm designed for 
exactly this application was described 
in the article "A Hobbyist Robot 
Arm," by Keith Baxter and Timothy 
Daly in the February 1979 BYTE, 
page 84... RSSj A less costly alter- 
native is to construct a chessboard 
which can electronically com- 
municate with the computer. The 
computer may then "look" at the 
board position through its l/0(in- 
put/output) ports. A means of in- 
dicating the computer's moves on the 
chessboard itself may also be pro- 
vided. 

In the system that I have con- 
structed, the user makes his move on 
the electronic chessboard, instead of 
typing each move on a keyboard. The 
computer's moves are displayed on 
the chessboard through the use of 
discrete light emitting diodes (LEDs), 
arranged in an X,Y coordinate sys- 
tem. The LEDs show the user exactly 
which chessman the computer wants 
to move, and to which square. 
In addition to being aesthetically 
pleasing, this system makes it im- 
possible to enter your move in- 



About the Author 

Jeff Teeters is an undergraduate student at 
the University of Wisconsin at River Falls 
where he majors in mathematics. 



34 September 1979 © BYTE Publications Inc 



correctly, and easy to interpret the 
computer's move. The board is 
continuously scanned so that even if 
the user moves the computer's piece 
incorrectly, the mistake is detected 
immediately. A speaker is connected 
to the computer to let unwary users 
know (by a buzz) when they misinter- 
pret a computer move. This speaker 
also emits a brief sound when the 
chess program has decided on a move 
and when it has been recorded into 
the computer's internal board 
representation. 

This project is designed for specific 
use with Peter Jenning's Microchess, 
running on a KIM-1 with about 0.5 K 
bytes of extra memory. Imple- 
mentation on other 6502 based com- 
puter systems should be relatively 
easy since only a few minor software 
modifications would be needed. The 
required hardware consists of a chess 
set, a package of cheap switching 
diodes, 2 integrated circuits, 16 
discrete LEDs and 32 copper rivets. 

The chessboard should have a thin, 
nonconductive surface that is easy to 
drill holes through. This surface must 
be supported by side panels so there is 
a hollow space of about 2 cm under 
the board for wiring. I used a cheap 
plywood chess set that is designed to 
fold into a storage box for the 
chessmen. The copper rivets should 
be small in diameter, about 12 mm 
long, and have a flat top. The ones 
that I used were size 9 rivets manufac- 
tured by the Tower Corporation of 
Madison IN. 

System Concepts 

KIM-1 Microchess uses an internal 
board-status table to keep track of the 
whereabouts of the chessmen. This 
table contains 32 square numbers 
which indicate the position of the 32 
pieces. It is important to realize that 
Microchess generates moves solely on 
the basis of what is in that table, and 
not how it was placed there. My plan 
of attack was simple. I had only to 
wire a chessboard to the computer 
and write an interface program that 
would translate moves on the chess- 
board into changes in the table. Since 
this program will be needed only 
when moves are physically being 
made, it can be called from 
Microchess and used in place of the 
Microchess keyboard I/O (input/out- 
put) routines. After the user has 
finished moving, control can be 




Photo 2: The bottom of the chessboard. The switching diodes and connecting wires are 
soldered directly to the wire contacts in the central holes. The 2 integrated circuits are 
type SN74154 decoder/demultiplexers. Note the tips of rivets protruding through some 
of the holes. 



transferred back to Microchess to 
compute the machine's next move. 

The Microchess to chessboard 
interface program is logically 
straightforward. If no move is being 
made, the table should be an accurate 
representation of the board. A move 
is detected when the table does not 
correctly represent the current board 
position. If an empty square appears 
on the board where the table indicates 
that a chessman resides, then the user 
has just picked up that man. If the 
table shows an unoccupied square 
which the board indicates is occu- 
pied, a chessman has just been set 
down in that square. A move is con- 
stituted by the user picking up a man 
and setting it down in some other 
location. A capture is completed by 
picking up 2 men and setting 1 down 
in the space formerly occupied by the 
other. Because the Microchess table is 
updated each time a simple move or 
capture is made, the table always 
gives an accurate representation of 
the current board position. 

Hardware Details 

Note that the chessboard interface 
program can keep track of the moves 
that are made simply by knowing if 
individual squares are occupied by a 
piece or are empty. The circuit which 




Photo 3: The complete chessplaying sys- 
tem. The completed electronic chessboard 
stands in the foreground. The chessboard 
and the sound-effect speaker are con- 
nected to the KIM-J computer residing in 
the suitcase in the background. 



provides this information to the com- 
puter is illustrated in figure 1. For 
purposes of square identification, the 
chessboard is conceptually cut in 
half. The 2 pieces are placed logically 
end to end, forming an arrangement 



September 1979 © BYTE Publications lnc 35 




2.S0/ 

BREAKING THE SOUND BARRIER 







THE TRAP DOOR 



33s6BT 



September 1977 



March 1979 



Byte Cover Prints - 
Limited Editions. 



The September '77 and March '79 covers of BYTE 
are now each available as a limited edition art print, 
personally signed and numbered by the artist, 
Robert Tinney. 

These prints are strictly limited to a quantity of 750 
for each cover, and no other editions, of any size, 
will ever be published. Each print is 18" x 22", 
printed on quality, coated stock, and signed and 
numbered in pencil at bottom. 



The price of each print is $25. This includes 1) a 
signed and numbered print; 2) a Certificate of 
Authenticity, also signed personally by the artist 
and witnessed, attesting to the number of the edi- 
tion (750), and the destruction of the printing plates; 
and 3) first class shipment in a heavy-duty mailing 
tube. 



To order your limited edition art print, 
mail the order form below. 



out and 



Send me "Breaking the Sound Barrier" 

prints at $25 each, and "Trap Door" 

prints at $25 each. I understand this price in- 
cludes Certificate of Authenticity and first class 
shipment. 

□ I have enclosed check or money order 
to Robert Tinney Graphics. 

□ Charge this to my Master Charge or Visa 



Card #_ 



Expires:. 



Ship my print(s) to: 
Name 



Address. 
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.Zip. 



Send order to: 

robert tinney graphics 

P.O. Box 45047 ■ Baton Rouge, LA 70895 



o 



36 BYTE September 1979 



Circle 369 on inquiry card. 



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Figure 1: Circuit which determines whether or not a given square is occupied. The chessboard is conceptually cut in half. It is placed 
so that the squares form a 4 by 16 matrix. For each square, a diode and a switch are wired in series between the appropriate row and 
column lines. A closed switch indicates an occupied square; an open switch indicates an empty square. 



of 4 rows and 16 columns. A diode 
matrix allows the hardware to iden- 
tify the individual squares. 

The integrated circuit in figure 1 is 
a type SN74154 4 to 16 line decoder/ 
demultiplexer. The 4 input lines to the 
device are connected to the KIM-1 
I/O port A. Each of the 16 output 
lines is linked to a column in the 
matrix. This portion of the circuit 
allows the KIM-1 to select 4 squares 
out of the total of 64. The 4 rows of 
the matrix are connected to the I/O 
port B. Row and column addressing 
allows scanning of a single square. 
Each square of the chessboard has a 
switch. A closed switch indicates that 
the square has a piece on it; an open 
switch shows that the square is 
empty. 

To determine whether or not a 
piece is on a particular square, the 
interface program first selects the 
column by sending the correct binary 



code to the 4 input lines on the 
SN74154. This brings 1 of the 16 out- 
put lines low, while the diodes keep 
the rest high. If the switch is closed 
(ie: a piece is on the square), then the 
corresponding row-line will be pulled 
low and the matching port-B data 
register bit will be a 0. Thus, by select- 
ing the column through port A and 
testing the row bits in port B, it is 
possible to determine the status of 
every square on the board. 

Switch Experimentation 

Now for the hard part: what can be 
used as a switch? The actual mechani- 
cal operation remains the only unre- 
solved detail. All that is needed is 
some means of closing the switch 
whenever a piece is set down, and 
opening it when one is picked up. 
There are several ways to accomplish 
this — some of which are better than 
others. 



In my first attempt I put aluminum 
foil on the bottom of the pieces and 
used simple wire contacts on top of 
the board. I punched 6 holes into each 
square using a large needle to form 
the corners of 2 concentric, equi- 
lateral triangles. Three strands of 
wire were looped through the holes 
forming 3 symmetric contacts (see 
figure 2a). The third contact was used 
only to balance the pieces. 

The concept is simple. The piece is 
set on top of the wire contacts and the 
aluminum foil makes the necessary 
connection. Unfortunately it didn't 
work. The contacts were not suffi- 
ciently stable, and the slightest vibra- 
tion rocked the pieces, leading the 
program to believe that the user was 
trying to move 5 or 10 pieces at once. 

That problem might have been 
solved by mounting magnets on the 
pieces and using a chessboard with a 
nonconductive magnetic surface. 



38 



September 1979 © BYTE Publications Inc 



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BYTE September 1979 39 




COLUMN 

Figure 2a: The first attempt to form a 
switch for the squares. Three symmetric 
contacts on top of each square were made 
by looping bare wire through holes in the 
board. Two of the contacts were wired to 
the row and column lines on the back side 
of the board. (The third wire was simply 
to balance the piece upright.) The pieces 
had aluminum foil glued to their bottoms. 
When such a chessman was set down on 
the contacts, electrical continuity was 
achieved. Unfortunately, vibration 
caused intermittent contact and confused 
the computer. 




COLUMN 

Figure 2b: The second attempt to form a 
square switch. This attempt was 
successful. Copper rivets were glued to 
the bottom of the chessmen. A large hole 
was drilled in the center of each square to 
receive the rivet. Two wires were looped 
through the large central hole from 2 
smaller holes (left over from the first 
switch attempt). The rivet closes the elec- 
trical circuit. 




ROW 



COLUMN 



Figure 2c: Illustration of the appearance of 
a square which uses rivet switches, and 
which previously did not have other 
methods installed in it. The reader may do 
it correctly the first time. 



Another possibility would be to 
eliminate wire contacts entirely and 
use reed switches or some type of 
photocell. Unfortunately, one such 
device must be mounted under each 
square, necessitating a total of 64 
devices. Although they would have 
undoubtedly worked, 64 photocells 
or reed switches would have cost 
more than I was willing to spend on 
the project. 

Switch Success 

I eventually figured out a contact 
method that was both cheap and 
reliable. I drilled a small hole in the 
center of each square, just large 
enough to slide in a copper rivet. Two 
strands of bare copper wire from 2 of 
the inner contact holes used in my first 
attempt were looped through the 
larger central hole forming 2 contacts 
inside of the hole (see figure 2b). The 
felt on the bottom of the pieces was 
peeled off and the tapered copper 
rivets were glued onto the metal 
weight underneath the felt with an in- 
stant bonding adhesive. 

I have found that these contacts 
work quite well. The tapered copper 
rivets slide easily in and out of the 
hole, while slight pressure from the 
sides of the hole forces the rivet to 
make good contact with the copper 



wire. The pieces remain intact and the 
electrical contacts remain solid, even 
when the chessboard is held upside 
down and shaken gently. Of course 
when you wire your chessboard, you 
should leave out the 3 symmetric 
wires that I tried on my first version. 
Only the 2 strands which were looped 
through the rivet hole need to be in- 
stalled (see figure 2c). 

Hardware for Computer Output 

The LEDs are wired according to 
figure 3. The integrated circuit is 
another 4 to 16 line decoder whose 4 
inputs are connected to the I/O ports. 
Note that decoder outputs thru 7 
are connected sequentially to the 
rank — indicating (Y axis) LEDs with 
the 0-bit output being connected to 
the uppermost LED. Likewise, the 
file — indicating (X axis) LEDs are 
connected left to right with outputs 8 
thru 15. The chip-enable line is con- 
nected to I/O port pin PBO so that the 
LEDs can be turned off while Micro- 
chess is computing a move. 

Mounting of the LEDs on the sides 
of the chessboard is relatively 
straightforward. I used a large needle 
to punch the holes for the leads prior 
to insertion. Glue can be used to hold 
them in place. Be sure to orient the 
chessboard so that a white square is 



in the lower right-hand corner of the 
side facing the human player. This 
means that the 2 rows of LEDs install- 
ed on the left side and bottom of the 
board will meet at a corner contain- 
ing a black square. 

The speaker is connected to output 
port pin PAO in the manner described 
in the K1M-1 User's Manual on page 
57. See figure 4 for an illustration of 
the I/O port connections. 

Software 

The necessary modifications to 
Microchess are shown in listing 1. 
The Microchess to chessboard inter- 
face program with source and object 
listing is given in listing 2. Although I 
used a nonstandard meta-assembler, 
most of the mnemonics are similar to, 
if not the same as, the MOS Techno- 
logy standard mnemonics. The 
listings are fairly well documented. 

There are, however, some general 
concepts that may be difficult to 
deduce from the listings. The 
workhorse of the chessboard inter- 
face program is subroutine GET- 
MOVE. GET-MOVE calls the KIM 
monitor routine GETKEY before 
doing anything else, in order to see if 
the user has pressed the DA key 
(which is used when setting up a new 
position) or the PC key (which clears 



40 



September 1979 © BYTE Publications lnc 



Y AXIS 



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02 


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20 


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32 j 33 


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44 § 46 | 




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62 


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OUTPUTS 
INPUTS 


ICI 
SN74I54 




Gl G2 


ABC! 


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KIM- 

1/0 

PORT 

1 
1 

PB-0 O 

1 
PA-5 \Z> 

1 
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1 
PA-7 £> 

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23 


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X 

axis" 



I 

Figure 3: Circuit for lighting the light emitting diodes (LEDs) that indicate the computer's move. The computer moves as follows. 
The program lights the X and Y axis LEDs which together indicate the single square on which the piece to be moved resides. The per- 
son picks up the indicated piece. After the user picks up the piece, different LEDs light up that point to the square to which the piece 
is to be moved. The person then places the chessman as indicated. A mistake causes the computer to emit a characteristic sound. 
The chip-enable line of ICl is connected to I/O (input/output) port pin PB so that the LEDs may be turned off while the chess pro- 
gram is computing its next move. 



September 1979 © BYTE Publications Inc 41 



the board for a new game). If neither square by square, searching for pieces 
the DA nor PC key is depressed, that were recently picked up or set 
GET-MOVE scans the chessboard, down. This is done by comparing the 




Bfl SPEAKER 



TO 
) CHESSBOARD 
COLUMNS 



) TO LEDs 



TO 
} CHESSBOARD 
ROWS 



Figure 4: Schematic diagram of chessboard input connections for the KIM-1. If the 
speaker is built into the chessboard, a 16 conductor cable is required to connect the 
board to the KIM-1 application connector. Thirteen conductors control the chessboard 
and light emitting diodes; 3 are needed for speaker, ground, and +5 V supply. The 
cable should be of sufficient length that the chessboard may be set in a convenient posi- 
tion for game playing. 



Microchess board-status table to 
the current board position, as pre- 
viously described. There is one im- 
portant exception. When the user 
picks up a piece to make a move, 
SHOULDBEUP-FLAG is made non- 
zero, and the square where the piece 
used to be is stored in hexadecimal 
addresses FA and F9. A nonzero 
SHOULDBEUP-FLAG tells sub- 
routine GET-MOVE that the 2 
squares in FA and F° should not be 
occupied, even if they are shown in 
the table. This is done to prevent 
GET-MOVE from continuously 
reporting that the same piece was 
picked up. 

Upon exit from the subroutine, the 
result of the search is stored in the 
accumulator and in location UP- 
CLEAR-DOWN. A +1 is returned if 
a piece has been picked up, a if there 
is no change, and a —1 if a piece was 
set down. If a piece was picked up or 
set down, then CHANGING- 
SQUARE will contain the number of 
the square where the pickup or set- 
down occurred. Likewise, if a piece 
was picked up, then CHANGING- 
PIECE will contain the hexadecimal 
designation of that piece as outlined 
on page 3 of the Microchess player's 
manual. 

While GET -MOVE is scanning the 
chessboard, it also lights up the X and 
Y axis LEDs that point to the square 
in LIGHT-SQUARE. If SPEAKER- 
FLAG is nonzero, the speaker is 
rapidly toggled to produce a hum. 

Subroutine CLEAR-STACK resets 
the Microchess and the machine stack 
pointers back to their initial values. 
The subroutine is called from various 
parts of the interface program to pre- 
vent the stacks from overflowing into 
Microchess code. 

After Microchess has computed 
each move, control is transferred to 
the start of the interface program at 
hexadecimal address 2000. The user 
must physically move the pieces for 
the computer. The piece designation 
and the from and to squares of the 
calculated move are stored in the 
KIM display at hexadecimal 
addresses FB, FA, and F9 respective- 
ly. Because of the no-operation in- 
structions inserted at address 03E1, 
the move has not been recorded in the 
board-status table. Addresses 2010 
through 2040 of listing 2 contain code 

Text continued on page 46 



42 September 1979 © BYTE Publications Inc 



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Listing 1: Modifications which were made to Peter Jennings' KIM-1 Microchess program 
to allow for the use of the electronic chessboard. Change the specified locations in 
memory with the KIM monitor. 



Address (Hexadecimal) New Code (Hexadecimal; 



0008 
000A 
00OD 
000F 
0012 
0033 
003F 
00B7 
00B9 
01AC 
03A7 
03E1 
03 E9 
03EC 



A9 


FF 




8D 


01 


17 


A9 


21 




8D 


03 


17 


4C 


00 


20 


00 






60 






02 


04 




08 


10 




60 






B1 






EA 


EA 


EA 


20 


39 


00 


4C 


00 


00 



Comments 

Set up Port A-DDR 

Set up Port B-DDR 

Jump to interface program 
Toggle, must be - 1 or zero 
Return from CLDSP 
MASK-TABLE (used 
to read row) 
Return from DISP 
Use. SQUARE for flag 
Don't record move 
Show all FFs 
(Concede defeat) 



Listing 2: The Microchess to chessboard interface routine, a sort of chessboard device 
handler program. This listing is the output of an assembly with both source and hexa- 
decimal object code shown. It is written in a nonstandard assembly language of the 
author's own design, although most of the mnemonics are similar to the MOS 
Technology standard mnemonics. 



0000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2000 
2002 
2004 
2006 
2006 
200A 



A? 00 

85 2F 

A5 FA 

85 2B 

E6 2E 



SET BIGC;0RG 2000; 

COMMENT *** KIM-1 MICROCHESS TO CHESSBOARD INTERFACE *** 
PROGRAM. URITTEN BY JEFF TEETERS. 9/8/78 



DEFINE 



-BOAKll=50, 

.6D-t=4F, 

.BK=40, 

.SF2=B2, 

.SQUARE'S!, 

CHANG1NG-SQUARE 

CHANGING-PIECE 

CLDSP-3900, 

CLEAR-BUARD=180 

C0UNT-FLAG=29, 

DISP=9D0I, 

FLASH-DISPLAY=1 

FR0M-SQUARE=2A, 

GETKEr = 4Alf , 

G0=A203, 

LlGHT-SQUARE=2B 

MASK-TABLE=B?, 

H0VE=4B03, 

P0RT-LIGHT=2C, 

P0RT-SQUARE=2D, 

P0RT-A=0O17, 

P0RT-B=0217, 

RAND0h»=O417, 

REVERSE=B202, 

SPEAKER-PLAG=2E 

SHOULDBEUP-FLAG 

SUnCH-FLAG = 30, 

TCHAN6ING-PIECE 

TL'HANGING-SUUAR 

TEMP=F3, 

TBGbLE=33, 

TUP-CLEAR-D0U 

UH0vE=3103, 

UP-CIEAR-D0UN 

-♦"=12, 



=2?, 
28, 

0, 
F1F, 



X ADDRESS UF PIECE I ABLE 

X .BOARD LESS ONE 

X ADDRESS OF USERS PIECES 

Z MICROCHESS STACK POINTER 

X TO SQUARE USED BY MOVE 

X RETURNED BY 6ET-M0VE 

X PIECE PICKED UP AT CH-SQR 

2 LLEAK DISPLAI 

X SET UP NEU GAME 

X SEI UHLN CUUNUNG D0UN 

X DISPLAY PIECE NAME IN FB 

X KIM MONITOR ROUTINE 

i USED UHEN UNM0VING CAPTURE 

X KIM MONITOR ROUTINE 

X ADDRESS OF CHESS PROGRAM 

X SQUARE LIGHTED BY LEDS 

X USED TO READ R0U 

X ROUTINE TO UPDATE .BOARD 

X USED TO BUILD 10 PORT 

X 

X KIM- I 1/0 PORT 



2F, 

-31, 

E=32, 



34, 
5, 



KIM-1 1NIERVAL TIMER 
RUUIINE TO EXCHANGE SIDES 
= 1, GET-MOVE GENERATES TONE 
=1, SQUARES IN FA X F9 UP 
SET IN tXCHANGE 
X TEMPURARY CHANGING PIECE 
X IEMPORAKY CHANGING-SUUARE 
TEMPORARY STORAGE L0CAI10N 
ALTERNATELY LIGHTS FA i F9 
TEMPORARY UP-CLEAR-D0UN 
ROUTINE TU UNMAKE MUVE 
STATUS OF CHANGING-SQUARE 
RETURN VALUE OF PLUS KET 



XXXXXXXXXXZXXZXXZXZXXXXXZIZZXXXXXZX7.1XX7.XZXXZXXZXXXX 

XXXXXXXXXX USER MOVE COMPUTER PIECE XXXXXXXXXX 

IXXXIXXXXXZXXXXXXXXXXXXZZXXXXZXXZXZXXZZIZXXIZZXIZXZX 

2****4**** PICK THE PIECE UP »********J| 



PICK-IT-UP: 



L U AM 00 

S(A SHOULDBEUP-FLAG 
FA 

L1GHI-SQUARE 
SPEAKER-FLAG 



LDA 
STA 

INC 
LOOP 



XRESET FLAG 



XLlGHl "PKUM SQUARE" 



XS0UND OFF 



44 September 1979 ( E' BYTE Publications Inc 



Circle 278 on inquiry card. 



200A 


20 


6B 


21 




JSR GET-MOVE 


XUAIT FOR PLAYER TO 


2001 


FO 








BED 


XZPICKUP PIELE. 


200E 


FB 








ENDLOOP 




200F 


30 


F7 






BH1 PICK- 11 UP 


XERkOR, PItCt SET DOUN 


2011 


A5 


27 






LUA LHANGING-SQUAKE 


21S P1LLE PICKED UP 


2013 


C5 


FA 






CMP Fh 


XZC0RREC1 ONE? 


2015 


DO 


F1 






BNE PICK-1TUP 




2017 


A6 


FB 






LDX FB 


XYES, SET TABLE ENTRY 


201? 


A? 


CC 






LOAD CC 


7.1 10 "CC" 


20IB 


?5 


50 






STAX .BOARD 




201D 










£****«**** SET THE PIECE 


DOUN ******♦**£ 


20ID 


A5 


F? 






LDA F? 


ZLIGHI TO SQUARE 


20 IF 


85 


2B 






S1A LIGHT-SQUARE 




202! 


E6 


2E 




SET 


IT-DUUN: INC SPEAKER-FLAG 


XHAKE NOISE 


2023 










LOOP 




2023 


20 


6B 


21 




JSR GET-MOVE 


XUAIT FOR CHANGES 


2026 


F0 








BEQ 




2027 


FB 








ENDLOOP 




2028 


A5 


F? 






LDA F? 


XIS USER MOVEING 


202A 


C5 


17 






CMP CHANGING- SQUARE 


XXCCJRRECT FIECf' 


202C 


DO 


F3 






BNE SET-IT-DUUN 




202t 


A5 


35 






LDA UP CLEAR-DOUN 


ZYES 


2030 


10 


08 






IF NEGATIVE THEN 




2032 


A6 


FB 






LDX FB 


ZUPOATE TABLE. (PIECE 


2034 


A5 


27 






LDA CHANGING-SOUARE 


ZXSET DOUN, MOVE HAS 


2036 


?5 


50 






STAX .BOARD 


ZXBEEN COMPLETED.) 


2038 


10 








BPL 




203V 


08 








ELSE 




203A 


A6 


28 






LUX CHANGING-PIECE 


XCAPTURED PIECE HAS 


203C 


A? 


CC 






LDAtl CC 


ZXBEEN PICKED UP... 


203t 


?5 


50 






STAX .BOARD 


ZXUPDATE TABLE AND 


2040 


30 


DF 






BUI SET-IT-DOUN 


XXUAIT FOR SET DOUN. 


2042 










ENDELSE 




2042 










nzzzzzzzzzzzzxxxzzzxzzxxzxxxxxzxxxzxxzzxxzxzxxxxxxx 


2042 










zzzzzzzzzxx user moue user's 


FIECE XXZXXXZXXX 


2042 










zzzzzzzxzzzzzzzzzzxzzzzzxzxzzzzzxzxzxzxzxzxzxzxzxxxz 


2042 


t6 


2E 






INC SPEAKER-FLAG 


ZMAKE NOISE 


2044 


A? 


00 




UAIT-FOR-HOVE: LDAK 00 


XCLEAR UP FLAG 


2046 


85 


2F 






STA SHOULDBEUP-FLAG 




2048 


85 


2? 




SET 


-COUNT: STA COUNT-FLAG 


XSET COUNT FLAG 


204A 


20 


3? 


00 


SET 


-D1SPLAV: JSR CLDSP 


ZCLEAR DISPLAY 


2041) 


20 


6B 


21 


GET 


-MOVE1: JSR GET -MOVE 




2050 


DO 


41 






IF ZERO THEN 




2052 










Z7.ZXZXXXZXZZXZXZXZXZXXXXXZX 


ZXZXZXXZXXXZXZXZXX 


2052 










ZZZXXZZX NO CHANGE IN 


BOARD XXXXXXXZ 


2052 










zzzzzzxzzzzzzzzzzzzzzzzzzzzzzzmzxxzxzzzzzxz 


2052 










It******** CHECK FOR "GO 


" KEY **<*******% 


2052 


20 


6A 


IF 




JSR GEIKEY 




2055 


C? 


13 






CNPtt 13 


XI3=VALUE OF "GO" KEY 


2057 


FO 


1/ 






BEQ GO-COUNTDOUN 




205? 










It******** CHECK FOR "E" 


KEY «**+****»X 


205? 


C? 


OE 






CMPH OE 




205B 


DO 


16 






IF ZEKU IHEN 


XUSER UANTS IU 


205D 










LOOP 


ZXSU1TCH SIDES 


205D 


20 


6A 


IF 




JSR GETKEY 




2060 


C? 


OE 






CMPtt OE 


XDEBOUNCE KEYBOARD 


2062 


FO 








BEQ 




2063 


F? 








ENDLOOP 




2064 


AS 


30 






LDA SUI1LH-FLAG 


X10GGLE FLAG 


2066 


4? 


FF 






EORK FF 




2068 


85 


30 






STA SU1TCH-FLAG 




206A 


20 


B2 


02 


SUIICH-SIDES: JSK REVERSE 


ZPERFORM EXCHANGE 


206D 


20 


5D 


21 




JSR CLEAR-STACK 




2070 


4C 


4C 


21 


60- 


;0UNTD0UN: JMP START-COUNTING 


2073 










ENDIF 




2073 










X*t*****« "uO" OR "E" NOT FOUND *+***+**Z 


2073 


A5 


2? 






LDA COUNT-FLAG 


XLGUNTING DOUN? 


2075 


FO 


12 






IF NOTZERO THEN 




2077 


C6 


FB 






DEC FB 


XYES. 


207? 


A5 


FB 






LDA FB 




207B 


DO 


06 






IF ZERO THEN 




207D 


20 


5D 


21 




JSR CLEAR-STACK 


XPLAY CHESS 


2080 


4C 


A2 


03 




JMP GO 




2083 










ENDIF 




2083 


A? 


OF 






LDAH OF 


XSTILL COUNTING DOUN, 


2085 


65 


2B 






ADC LIGH1-SQUARE 


XZLIUHT NEXT SQUARE. 


2087 


DO 








BNE 




2088 


03 








ELSE 














Listing 2 continued on page 46 




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SYSTEMS INC. 




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Northridge, CA 91324 

Phone: (213) 349-9076 ^/ 

September 1979 © BYTE Publications lnc 45 



Listing 2 continued from page 45: 



2089 


All 


04 17 ! 


208C 






208C 


85 


2B ! 


208E 


A5 


FB ! 


2090 


4C 


4A 20 ! 


2093 






2093 


10 


49 ! 


2095 






2095 






2095 






2095 






2095 


A5 


B2 ! 


2097 


C9 


C8 ! 


2099 


F0 


01 ! 


209B 


A5 


2A ! 


20911 


C5 


27 ! 


209F 


DO 


06 ! 


20AI 


20 


31 03 ! 


20A4 


4C 


44 20 ! 


20A7 






20A7 






20A7 






20A7 


20 


6A IF ! 


20AA 


C9 


15 ! 


20AC 


10 


IC ! 


20AE 


C9 


12 ! 


20B0 


DO 


OC ! 


20B2 


A5 


FA ! 


20B4 


10 


97 ! 


20B6 


A6 


FB ! 


20B8 


A5 


1 7 | 


20BA 


95 


50 ! 


2061 


10 


86 ! 


20BE 






20BE 


85 


F3 ! 


20C0 


A5 


FB ! 


20C2 


0A 


OA ! 


20C4 


0A 


OA ! 


20C6 


05 


F3 ! 


20C8 


85 


FB ! 


20CA 






20CA 


A5 


2,' ! 


20CC 


85 


2B ! 


20CE 


85 


F9 ! 


20D0 


A5 


FB ! 


20D2 


29 


IF ! 


20D4 


85 


IB ! 


20DA 


AA 




20D7 


B5 


50 ! 


20D9 


B5 


FA ! 


20DB 


4C 


4D 20 ! 


20DE 






20DE 






20DE 




! 


20BE 






20DE 






20DE 


A5 


B1 ! 


20E0 


L9 


CC ! 


20E2 


DO 


05 ! 


20E4 


E4 


B1 ! 


20E6 


4C 


6A 20 ! 


20E9 






20E9 






20E9 


20 


5D 21 ! 


20EC 


A5 


27 ! 


20tE 


85 


1 A ! 


20F0 


85 


F9 ! 


20F2 


8b 


2B 1 


20F4 


20 


9D 01 ! 


20F7 


A9 


01 ! 


20F9 


85 


2F ! 


20FB 






20FB 


20 


6B 21 ! 


20FE 


FO 




20FF 


FB 




2100 






2100 


10 


11 ! 



XUAITING FOR (1UVE... 
XXLIGHT RANDOM SQUARE 



LDA? RANUGMH 

ENDELSE 

STA LIGHT-SQUARE 

LDA FB 

JMP SET-DISPLAY 
ENDIF 
IF NEGATIVE THEN 

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxr.xxxxxxxxnxxx 

XXXXXXXX NEU PIECE SE1 DOUN XXXIXXXX 

XXXXXXXXXXXXXXXXXXXXXXXXXXXIXXXXXXXXXXXXXXXXX 
j>«*M**»* TAKING BACK CAPTURE? *********Z 
LDA .SP2 

CMP* C8 XUNLI01NU PREVIOUS 

IF NOTZERO THEN XI CAPTURE? 
LDA FR0H-S9UARE 
CMP CHANGING-SQUARE 
IF ZERO THEN 

JSR UHOVE X YES. 

JHP UHlT-FOR-MOVE 
ENDIF 
ENDIF 
2!*********USER ADDING NEU PIECE**********?; 
JSR GEIKEY XUAlf FOR KEY ENTRY 



CHPH 15 


XXilf HEX NAME UR " + " 


IF NOTZERO 1HEN 




CMPM "+" 




IF ZERO THEN 




LDA FA 


XFOUNP "+", ENTER NEU 


BPL GET-H0VE1 


UPIECE INTO TABLE IF 


LDX IB 


XXNOT IN ALREADY 


LDA CHANGING- 


SQUARE 


STAX .BUARD 




BPL UAIT-FOR- 


flUVE 


ENDIF 




STA TEHF 


2FUUND HEX DIGIT 


LDA FB 


U"OR" IT INTO 


ASL ASL 


XZPUIL NAHE. 


ASL ASL 




ORA TEHP 




STA TB 




ENDIF 




LDA CHAN&ING-SQUAKt 


ZBUiLU DISPLAY 


STA LIGHT-SQUARE 




STA F9 


XUF9=SQUARE ON BOARD 


LDA FB 


XPU1 PIECE NAME IN 


ANDti IF 


URANGE 


STA FB 


UXFB=PIEL'E NAME 


TAX 




LDAX .BOARD 




STA 1- A 


XXXFA=TABLE EN1RY 


JHP GET- MOVE 1 





ENDIF 

7.XXXXXXXXXXXXXXXXXXXXXXXXXXXIXZXXIXXXXXXXXXXX 

XXXXXXXX PIECE PICKED UP XXXXXXXX 

XIXXXXXXXXXXXXIXXXXXXXXXXXXXIXXXXXXXXXXXXZXXX 

IW**M**M USER PLAY UHITE' **«*******X 



LDA .SQUARE 




JSEE IF USER MAKING 


CHP« CC 




XXTHE FIRST MOVE. 


IF ZERO IHEN 






INC .SQUARE 




ZYES, CHANGE .SQUARE 


JMP SUITCH-SIDES 




HAND EXCHANGE 


ENDIF 






X«*+t****** gAIT FOR 


CHANGt ♦*********% 


JSR CLEAR-S1ACK 




XLLtAK POSSIBLE JUNK 


LDA CHANGING-SQUARE 






STA FA 




ZDISPLAT SQUARE NUrt 


STA F9 






STA LIGHT-SQUARE 






JSR DISP 




ZD1SPLAY PIECE NAME 


LDA* 01 






STA SHOULDBEUP-FLAG 




XSET FLAG 


LOOP 






JSR GET-HUVE 




ZAUAIT M0VE2 


BEQ 






ENDLOOP 






2********* PIECE SET BACK 


DOUN **********% 


IF NEGATIVE THEN 






L 


sting 2 continued on page 48 



Text continued from page 42: 

to light the correct LEDs and modify 
the board-status table as the user 
completes the computer's move. The 
speaker sounds briefly after each cor- 
rect step is completed. If a wrong 
piece is moved or a piece is set down 
on a wrong square, the speaker will 
hum continuously to signal an error. 

The logic for interpreting the user's 
move starts at location 2042. If 
COUNT-FLAG is 0, the user has not 
yet moved. Subroutine GET -MOVE 
is repeatedly called from location 
204D in anticipation of the user's 
move. 

If the accumulator is upon return 
from GET-MOVE, then the board 
position remains unchanged and the 
user has not made a move. GETKEY 
is called to see if the user has de- 
pressed either the GO or E key. If the 
E key is depressed, the Microchess 
routine REVERSE is called to swap 
the user and computer entries of the 
board-status table. After the ex- 
change is completed or if the GO key 
is depressed, a branch is made to 
START-COUNTING at hexadecimal 
address 214C. 

Three provisions are made for a 
delayed return back to Microchess. 
COUNT-FLAG is made nonzero, a 
countdown is initiated by setting the 
display to OF, and control is then 
transferred back to address 204D 
where GET -MOVE is repeatedly 
called as before. 

After each return from GET- 
MOVE the display is decremented by 
1 until it equals 0. This provides an 
approximate 10 second delay during 
which the user can make a new move 
or retract an old one. At the end of 
the countdown, a branch is made to 
the Microchess routine GO which 
calculates the computer's next move. 

If the GET-MOVE call at 204D 
returns a negative value then the user 
has set down a new piece, and control 
is transferred to address 2095. In an 
ordinary game of chess, putting a 
new piece on the board would be con- 
sidered cheating. I have allowed it 
here to prevent 2 possible problems. 

The first problem is caused by in- 
decisive players who change their 
minds while in the middle of a move. 
Suppose such a player picks up 2 
chessmen, as if to capture, and then 
decides to set both down again. When 
the first man is set down the program 
will think that the user has completed 
a capture, modify the board-status 



46 September 1979 '& BYTE Publications Inc 



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CORVUS SYSTEMS, Inc. 



900 S. Winchester Boulevard 
San Jose, California 95128 
408/246-0461 



Circle 83 on inquiry card. 



BYTE September 1979 47 



Listing 


2 continued from page 46 






2102 


A5 27 ! 




LDA CHANGING-SQUARE 


XFROM SQUARE = 


2104 


C5 FA ! 




CMP FA 


XXTO SQUARE? 


2106 


DO 03 l 




IF ZERO THEN 




2108 


4C 44 20 ! 




JHP UAIT-FOR-MOVE 


XYES, NO MOVE MADE. 


210B 






ENDIF 




210B 


85 B1 ! 




STA .SQUARE 


XNO, 


2I0D 


20 4B 03 I 




JSR MOVE 


XZRECORD MOVE, 


2110 


4C 4C 21 




JHP START-COUNTING 


HAND COUNT DOUN. 


2113 






ENDIF 




2113 






XXXXIXIIXXXZXZXXXXXXXXXIXXXXIXXXXXZXIXXIXXXXX 


2113 






zxxxxzxx 2'nd piece picked up ixxxzxxx 


2113 






XZXXIZZXXXXXZZZXXZXXXXXXXXZZXZXXXXXXXXXXXXXXX 


2113 






X********* UAIT FOR SET 


DOUN **»*****#3I 


2113 


A5 27 




LDA CHANGING-SQUARE 




2115 


85 F? 




STA F? 


XF?=TO SQUARE 


2117 


85 Bl 




STA .SQUARE 




211? 




2-UP: 


LOOP 




211? 


A5 33 




LDA TOGGLE 


ZFLASH LIGHTS FOR TO 


2MB 


10 06 




IF NEGATIVE THEN 


HAND FROM SQUARES. 


21 1 D 


A5 FA 




LDA FA 




2I1F 


E6 33 




INC TOGGLE 




2121 


FO 




BEQ 




2122 


04 




ELSE 




2123 


A5 F? 




LDA F? 




2125 


C6 33 




DEC TOGGLE 




2127 






ENDELSE 




2127 


85 2B 




STA LIGHT-SQUARE 




212? 


20 6B 21 




JSR GET-MOVE 


ZUAIT FOR SET DOUN 


21 2C 


FO 




BEQ 




21 2D 


EB 




ENDLOOP 




21 2E 


10 2? 




IF NEGATIVE IHEN 




2130 






%********* PIECE SET DOUN *********J 


2U0 


A5 27 




LDA CHANGING-SQUARE 




2132 


C5 F? 




CMP F9 


3X-S = TO SQUARE? 


2134 


FO OC 




IF NOTZERO THEN 


XXNOPE, 


2134 


C5 FA 




CMP (A 


Z= FROM SQUARE? 


2138 


DO IF 




BNE ERROR-3 


XXNOPE, ERROR 


21 U 


A6 F? 




LDX F? 




2I3C 


85 F? 




STA F9 


XTO X FROM SQUARES 


21 3E 


65 Bl 




STA .SQUARE 


ZREVERSED, SUITCH BACK 


2140 


H6 FA 




STX FA 




2142 






ENDIF 




2142 


A5 FA 




LDA FA 


ZSAVE FROM SQUARE FOR 


2144 


85 2A 




STA FROM SQUARE 


ZXUSE IF UNDOING MOVE 


2146 


20 ?D 01 




JSR DISP 


ZSET .PIECE 


214? 


20 4B 03 




JSR MOVE 


ZRECORD MOVE 


21 4C 






2********* INITIALIZE COUNT DOUN ********* 


214C 


A? 00 


START-COUNTING: LDAH 00 


XCLEAR FLAG 


2I4E 


85 2F 




STA SHOULDBEUP-FLAG 




2150 


85 2B 




STA LIGHT-SQUARE 




2152 


A? OF 




LOAN OF 


XLUAC DELAY 


2154 


E6 2E 




INC SPEAKER-FLAG 


ZSOUNII OFF 


2156 


4C 48 20 




JHP SET-COUNT 




215? 






ENDIF 




215? 


E4 2E 


ERROR-3: 


INC SPEAKER-FLAG 


XSOME TYPE OF" ERRUR, 


215B 


DO BC 




BNE 2-UP 


XZUAIT UNTIL CORRECTED 


213D 










215D 










215D 










215D 




SUBROUTINE 


CLEAR-STACK: XRESETS BOTH STACK MARKERS 


2I5D 


68 A8 68 




PLA TAY PLA 


ZSTORE RETURN ADDRESS 


2160 


A2 FF ?A 




LDXH FF TXS 


ZRESET MACHINE STACK 


2143 


A2 C8 




LDX* C8 


ZRESL1 CHESS STACK 


2165 


86 B2 




STX .SP2 




2167 


48 ?8 48 




PHA TYA PHA 


ZSET UP RETURN 


216A 


60 




RTS 




2I6B 










2148 










216B 










214B 




! SUBROUTINE 


GET-MOVE: XSCANS 


CHESSBOARD 


216B 




! UUXHUUUllllUUUXUlXlXUUUXXXUlZlU%lXTt.U 


216B 




! xxxxzxxzzzz check for "da" 


OR "PC" XXXXXXZXXZ 


216B 




! luxuuuxuxxuxxxiuvaiun 


XZXZXXXXXXXZXZXZZXXXl 


2I6B 


20 6A IF 




JSR GETKEY 




216E 


C? 11 




CHPK 11 


XI 1 = "HA" KEY 


2170 


DO OB 




IF ZERO THEN 




2172 


A2 IF 




LDXH IF 


ZFOUND "DELETE ALL" 



Listing 2 continued on page 50 



table accordingly, and proceed to 
countdown. During the countdown 
the second man would pop in and 
there would be no way to know what 
it was. 

In order to prevent this, each cap- 
turing move is saved in the 
Microchess stack. When a new piece 
is set down, the stack pointer is 
checked to see if the previous move 
was a capture. If it was, and if the 
location of the new piece corresponds 
to the square where the capturing 
piece used to be, then the Microchess 
routine UMOVE is called to restore 
the board-status table. 

The second problem arises when 
the user wants to add new pieces to 
the current board, or set up an entire- 
ly new board position. Previously the 
only way to add new pieces was to 
stop the chess program and enter the 
square numbers manually into the 
board-status table using the KIM-1 
monitor. This method is both incon- 
venient and error prone. The control 
logic for the "new improved" method 
occupies hexadecimal addresses 20A7 
through 20DE. 

After setting the new pieces down, 
the user simply types the piece name 
(its numeric designation) into the 
hexadecimal keyboard. The designa- 
tion is displayed in FB, the current 
board-status table entry in FA, and 
the square where the new piece was 
set down is stored in F9. If the current 
table entry is "CC" (indicating that 
the piece is not currently on the 
board), the user may enter the piece 
into the table by pressing the + key. 

Interpreting the User's Move 

If the original call to GET-MOVE 
at hexadecimal address 204D returns 
a positive value, it means that the 
user has picked up a piece, and con- 
trol will transfer to address 20DE. If 
.SQUARE contains "CC", the Micro- 
chess board-status table has just been 
initialized, and the user is making the 
first move of a new game. The board- 
status table has been initialized 
assuming that the user would play 
Black. A branch may be made to 
address 206A where the user and 
computer table entries are exchanged. 
After checking to see whether or 
not the user is playing White, GET- 
MOVE is again called at hexadecimal 
address 20FB. If the piece is set down 
at a new square, the move has been 
completed and a countdown is 
started. If, after picking up a piece a 



48 



September 1979 © BYTE Publications Inc 



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■ Eight software-selectable 
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Call toll-free 800-343-6412. 

In Massachusetts, Alaska, and Hawaii 
call (617) 237-7610. 



« 



Circle 176 on inquiry card. 

Integral Data Systems, Inc. 



Listing 


2 continued from page 48: 


2174 


A9 


cc 




LDAtt CC 


2174 








LOOP 


2176 


95 


50 




STAX .BOARD XFILL PIECE TABLE 


217B 


CA 






DEX UUITH "CC" 


2179 


10 






BPL 


21 7A 


FB 






ENDLOOP 


217B 


30 


1F 




BHI JMP-TO-HAIN 


217D 








ENDIF 


217D 


C9 


14 




CMP* 14 X14="PC" KEY 


217F 


DO 


21 




IF ZERO THEN UIPLEASE CLEAR) 


2181 


20 


18 


00 


JSR CLEAR-BOARD XSET UP NEU GAME 


21S4 


85 


B1 




STA .SQUARE XFLAG .SOUARE UITH CC 


2186 


A9 


00 




LOAN 00 ZCLEAR FLA6S 


2188 


85 


2F 




STA SHOULDBEUP-FLAG 


218A 


85 


30 




STA SUITCH-FLAG 


218C 








LOOF XUAIT FOR CLEAR BOARD 


2I8C 


A5 


27 




LDA CHANGING-SQUARE 


218E 


85 


F9 




STA F9 XBISPLAY BAD SQUARE 


2190 


85 


FA 




STA FA 


2192 


85 


2B 




SfA LIGHT-SQUARE 


2194 


20 


9D 


01 


JSR BISP XD1SPLAT PIECE NAME 


2197 


20 


A2 


21 


JSR START-SCAN 


219A 


DO 






BNE 


219B 


FO 






ENDLOOP 


219C 


20 


5D 


21 


JNP-TO-NAIN: JSR CLEAR-STACK IRESET STACK 


21 9F 


4C 


44 


20 


JHP UAIT-FOR-HOVE 


21A2 








ENDIF 


21A2 








muzuuuuiuxxunuumuxmnuuuuuuu 


21A2 








UXUlUXll START SCANNING CHESSBOARD UXXIXXXXX 


2IA2 








XXXIZXXXZZIIZIXZZXXZXXIXIXIZXZZIXZXZXZXIXIXUZZZXXZX 


21A2 








X********* SET UP PORT-LIGHT **«******2 


21 A2 


A5 


30 




START-SCAN: LDA SUITCH-FLAG XSIDES EXCHANGED? 


2IA4 


FO 


07 




IF NOTZERO THEN 


2IA6 


A5 


2B 




LDA LIGHT-SQUARE XYES, 


2IA8 


49 


77 




EORII 77 ZXPL=77-"LIGHT-SGUARE 


2IAA 


4C 






JHP 


2IAB 




AF 


21 


ELSE XNU, 


2 IAD 


A5 


2B 




LDA LIGHI-SUUARt XXPL="tlGM r-SOUARL" 


21 AF 








ENDELSE 


2IAF 


85 


2C 




STA PORT -LIGHT 


2IB1 








Z********INITIALIZE U-C-D * TC-S****»***X 


2IB1 


A9 


00 




LOAD 00 


2IB3 


85 


35 




STA UP-CLEAR-UUUN 


21 B5 








LOOP 


21 B5 


85 


32 




STA fCHANGING-SQUARE 


21B7 








J<*********D0 MISCELLANEuUS 1/0**********2 


21B7 


20 


IF 


IF 


JSR FLASH-DISPLAY IFLASH DISPLAY 


21BA 


A5 


2E 




LDA SPEAKER-FLAG 


21BC 


FO 


03 




IF NOTZERO 1HEN 


21 BE 


EE 


00 


17 


INC9 PORT-A ITOGBLE SPEAKER 


21C1 








ENDIF 


21C1 








IXXXXXXXXXXXXXXXXUXXIXIXXXXXXIXXXXXXXXXIXXXX 


21C1 








XXXXXXXX IF SHOULDBEUP-FLAG NOf SET XXXXXXXX 


21C1 








XlllXllX SEE IF SQUARE IN PIECE TABLEXXIXXXXX 


2IC1 








zxxxxxzzzxxxxxxxzxxxxxxxxxzzxxxzixxzixxxxxzxx 


21C1 


A9 


00 




LDAtt 00 XASSUNE SQUARE OK 


21C3 


85 


34 




STA TUP-CLEAR-DOUN 


21C5 


A5 


2F 




LDA SHOULDBEUP-FLAG JIN MIDDLE OF MOVE? 


21C7 


FO 


OA 




IF NOTZERO THEN 


21C9 


A5 


32 




LDA TCHANGING-SQUAREZYES, IS SQUARE IN 


21 CB 


C5 


FA 




CHP FA XXDISPLAY? IF SO 


21 CD 


FO 


15 




BEQ NOT -IN-TABLE XXPRE1EHH THAT IIS 


2ICF 


C5 


F9 




CHP F9 IXNOT IN PIECE TABLE. 


2191 


FO 


11 




BEQ NOT-IN-TABLE 


21D3 








ENDIF 


21D3 








X**********SEAKCH PIECE TABLE********** *X 


21 D3 


A2 


IF 




LDXIt IF 


21D5 








LOOP 


21B5 


B5 


50 




LDAX .BOARD 


21D7 


C5 


32 




CMP ICHANGING-SUUARt 


21D9 


DO 


06 




IF ZERU IHEN 


21 DB 


86 


31 




STX TCHANGING-PIECE 


21DD 


E6 


34 




INC TUP-CLEAR-DOUN ZFOUND SQUARE 


21DF 


DO 


05 




BNE BUILD-PORTS 


2tE1 








ENDIF 


21E1 


CA 






DEX 


2IE2 


10 






BPL 



Listing 2 continued on page 52 



player decides to set it down on the 
same square, the move is ignored. 

If the GET-MOVE call at location 
20FB reports that a second piece has 
been picked up, a capture is in pro- 
gress and control branches to location 
2113. FROM-SQUARE is defined as 
the square from which the first chess- 
man is picked up. Similarly, TO- 
SQUARE is associated with the 
chessman that is picked up second. 
GET -MOVE is again called at hexa- 
decimal address 2129. 

If a piece is set down on either the 
TO or FROM squares then the pro- 
gram assumes that a capture has been 
made. The Microchess routine 
MOVE is called to modify the board- 
status table, and a countdown is ini- 
tiated. 

If a piece is set down on a square 
other than the FROM or TO square, 
or if a third piece is picked up, a 
branch will be made to hexadecimal 
address 2159, and the speaker will 
hum to indicate an error. 

Using the System 

Playing the chessboard-interfaced 
version of Microchess is easy. Moves 
are made by physically picking up the 
pieces and setting them down on a 
new square, as in a normal game of 
chess with a human opponent. The 
only difference is that the opponent 
(the KIM-1) is unable to pick up a 
chessman, so you have to move the 
pieces to the location indicated by the 
LEDs. 

The KIM display will be all Os and 
the LEDs will blink from square to 
square in a semirandom fashion when 
it is your turn to move. After you 
move, the KIM display will count- 
down from OF, and the Y axis LEDs 
will blink sequentially from the top to 
the bottom of the board. During this 
countdown you have the option to 
change your move. When the display 
reaches 0, the machine will begin 
computing a response, and no moves 
can be made until it is your turn 
again. 

Operating the System 

The interfaced version of 
Microchess is started at address 0000, 
just as the unmodified Microchess. 
The speaker will probably hum. To 
start a new game, press the PC key. 
The speaker's sound will cease. 
Choose the White or Black pieces, 
and set up the board with your choice 



50 September 1979 © BYTE Publications Inc 




Solve your personal energy crisis. 

Power do the work. 



With a calculator, pencil and paper you can spend hours plan- 
ning, projecting, writing, estimating, calculating, revising, erasing 
and recalculating as you work toward a decision. 

Or with VisiCalc and your Apple* II you can explore many 
more options with a fraction of the time and effort you've spent 
before. 

VisiCalc is a new breed of problem-solving software. Unlike 
prepackaged software that forces you into a computerized 
straight jacket, VisiCalc adapts itself to any numerical problem 
you have. You enter numbers, alphabetic titles and formu- 
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information on the screen. You don't have to spend your 
time programming. 

Your energy is better spent using the results than 
gettirig them. 

Say you're a business manager and want to project 
your annual sales. Using the calculator, pencil and 
paper method, you'd lay out 12 months across a 
sheet and fill in lines and columns of figures 
on products, outlets, salespeople, etc. You'd 
calculate by hand the subtotals and summary 
figures. Then you'd start revising, erasing 
and recalculating. With VisiCalc, you simply 
fill in the same figures on an electronic 
"sheet of paper" and let the computer do 
the work. 

Once your first projection is complete, 
you're ready to use VisiCalc's unique, 
powerful recalculation feature. It lets you 
ask "What if?" examining new options and 
planning for contingencies. "What if" sales 
drop 20 percent in March? Just type in the 
sales figure. VisiCalc instantly updates a 
other figures affected by March sales. 

Circle 301 on inquiry card. 



Or say you're an engineer working on a design problem and are 
wondering "What if that oscillation were damped by another 10 
percent?" Or you're working on your family's expenses and 
wonder "What will happen to our entertainment budget if the 
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instantly to show you all the consequences of any change. 

Once you see VisiCalc in action, you'll think of many more 
uses for its power. Ask your dealer for a demonstration and dis- 
cover how VisiCalc can help you in your professional work and 
personal life. 

You might find that VisiCalc alone is reason enough to 
i own a personal computer. 

VisiCalc is available now for Apple II computers, with 

'versions for other personal computers coming soon. The Apple 

II version costs just $99.50 and requires a 32k disk system. 

For the name and address of your nearest VisiCalc 

dealer, call (408) 745-7841 or write to Personal 

Software, Inc., Dept. B, 592 Weddell Dr., 

Sunnyvale, CA 94086. If your favorite 

> .1 dealer doesn't already carry Personal 

Software products, ask him to 

give us a call. 




0R0 



TM— VisiCalc is a trademark of 

Personal Software, Inc. 
'Apple is a registered trademark 
of Apple Computer, Inc. 



Listing 

21E3 

21 E4 

21E6 

21E4 

21 E4 

21E4 

21E4 

2tE8 

21EA 

21 EC 

21EE 

21 EF 

21 F1 

21F3 

21F3 

21 F5 

2IF5 

21F7 

21F9 

21FB 
21FD 
21 FD 
21FF 
2202 
2203 
2205 
2207 
220A 
220C 
220F 
2211 
2213 
2214 
221 B 
221A 
221B 



2 continued from page 50: 
Ft ! ENDL0OP 

C4 34 1N0T-IN-TABLE: DEC TUP 



CLEAR-MIUN XSQUAKE NO! IN .BUAKD 



A5 30 
FO 07 
A5 32 
49 77 
4C 

F3 21 
AS 32 

85 2D 

A5 2C 
30 04 
OA OA 

OA OA 

2V 70 
EE 02 17 
OA 

85 F3 
A9 01 
2D 00 17 
05 F3 
8D 00 17 
A5 2D 
29 40 
4A 4A 4A 
05 2D 
29 OF 
OA 
OU 00 17 



xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxixxxxxxxxxx 
xxxxxxxxx build i/o forts zmum 

zzmmmzmmmxxzmmmmnmzzzz 

X***»******SET UP PORT-SQUARE****»*«*«*+X 



BUILD-PORTS: 



LDA 


SUITCH-FLAG 


XSIDES EXCHANGED? 


IF N01ZER0 THEN 




LDA TCHANGING 


-SUUARt XrES, SET PS TO 


EORJ 77 


ZX77-"TCH-SQUARE' 


JHP 




ELSE 




XNO, 


LDA TCHANGING 


-SQUARE ZXPS="TCH-SUUARE' 


ENDELSE 




STA 


PORT-SQUARE 




)>****++*****+***PfjR| - 


ft -ft ******** »***»■■* *X 


LDA 


PURT-LIGHI 




IF POSITIVE THEN 






*SL ASL 


XNEGATIVE=X AXIS, 




*SL ASL 


XFObITIVE=Y AXIS. 


ENDIF 




AND* 


70 




INC? 


PORT-B 


XDI5ABLE LEDS 


ASL 




XLON [ TOGGLE SPEAKER 


STA 


TEMP 




LUAtt 


01 




ANDfi 


P0R1 -A 




OKA 


TEMP 




STAB 


PURT-A 


XSTORE ALL BUT COLUMN 


LDA 


PORT-SQUARE 




AND* 


40 




LSR 


LSR LSR 




ORA 


PORT-SQUARE 




ANDI 


OF 




ASL 






0RA6 


PORI-A 





Listing 2 continued on page 54 



of color placed closest to the bottom 
X axis LEDs. After the chessmen are 
in place, the display will show all Os. 
If you are playing White, make your 
opening move. If the computer is 
playing White, press the GO key. 

To set up the pieces in a new con- 
figuration, or to continue a game that 
was halted earlier, set the chessboard 
up with the chessman in their desired 
position. Start the chess program as 
described above, but instead of press- 
ing the PC key, press the DA key. 
Type in the name of each piece using 
the hexadecimal keyboard as you 
would when adding a new piece. 
Start the play by either making a 
move or by pressing the GO key. 

To add a new piece to the board, 
set the piece on the desired square. 
The KIM-1 display will show 3 bytes 
of information. The first byte will be 
a random piece designation (as 
described on page 3 of the Microchess 
player's manual). The second byte is 
the square that the piece is on, 
according to the Microchess board- 
status table. If the piece has been cap- 
tured, "CC" will be displayed. The 
third byte is the number of the square 




PET TRS-80 Compucolor II 

ADD SOUND TO YOUR BASIC PROGRAMS! 



Complete system includes hardware with 
connectors and software that provides all 
the tools for programming you need to 
make sound. You get: 

• a variety of sample sound effects and 
musical notes 

• directions to easily create your own 
sounds and tunes 

• complete instructions, including sample 
BASIC subroutines, for adding sound to 
any program. 



Also, SOUNDWARE SOFTWARE 

programs for 8K PET. 

SEE YOUR DEALER FOR A 

DEMONSTRATION. 

Suggested Retail: 

PET/TRS-80 $29.95 Compucolor S39.95 

CAP Electronics, 1884 Shulman Ave. 

San Jose, CA 95124 (408) 371-4120 



52 September 1979 © BYTE Publications Inc 



Circle 43 on inquiry card. 



PET / TRS-80 1 A PPLE: Personal Software brings you the finest! 

Ml 




CHESS 

The Industry's First 

Gold Cassette 

Over 50,000 Sold 



MICROCHESS is the industry's best selling computer game. And 
no wonder— because MICROCHESS gives you more than just a 
chessplaying program: A convenient, foolproof set of commands 
and error checks ... complete instructions in a 5V4" by &V2" booklet ... 
a cassette that's guaranteed to load, with disk versions coming 
soon ... and several levels of difficulty to challenge you not just 
once, but time after time. It's available through well over three 
hundred computer stores and many mail order sources ... always 




originating from Personal Software. What's more, every Personal 
Software product is selected to give you these same benefits of 
easy availability, reliable cassettes, readable documentation, a 
carefully thought out user interface ... and most important, 
continuing challenge and enjoyment, not just once but time after 
time. If you haven't already, order your own gold cassette: 
MICROCHESS, by Peter Jennings, for 8K PETs, 16K APPLEs, and 
4K Level I and II TRS-80S $19.95 




TIME 
TREK 

A Tour De Force 

In Real Time Action 

Strategy Games 



TIME TREK by Brad Templeton for 8K PETs and Joshua Lavinsky 

for 4K Level I and II TRS-80S adds a dramatic new dimension to the 
classic Star Trek type strategy game: REAL TIME ACTION! You'll 
need fast reflexes as well as sharp wits to win in this constantly 
changing game. Be prepared— the Klingons will fire at you as you 
move, and will move themselves at the same time, even from 
quadrant to quadrant — but with practice you can change course 
and speed, aim and fire in one smooth motion, as fast as you can 
press the keys. Steer under power around obstacles— evade enemy 




shots as they come towards you — lower your shields just long 
enough to fire your phasers, betting that you can get them back up 
in time! With nine levels of difficulty, this challenging game is easy 
to learn, yet takes most users months of play to master. ADD 
SOUND EFFECTS with a simple two-wire hookup to any audio 
amplifier; the TRS-80 also produces sound effects directly through 
the keyboard case, to accompany spectacular graphics 
explosions! You won't want to miss this memorable version of a 
favorite computer game $14.95 






BLOCKADE by Ken Anderson for 4K 

Level I and II TRS-80s is a real time 
action game for two players, with high 
speed graphics in machine language. 
Each player uses four keys to control 
the direction of a moving wall. Try to 
force your opponent into a collision 
without running into a wall yourself! A 
strategy game at lower speeds, 
BLOCKADE turns into a tense game of 
reflexes and coordination at faster 
rates. Play on a flat or spherical course 
at any of ten different speeds. You can 
hear SOUND EFFECTS through a 
nearby AM radio— expect some 
razzing if you lose! 14.95 



GRAPHICS PACKAGE by Dan Fylstra 
for 8K PETs includes programs for the 
most common 'practical' graphics 
applications: PLOTTER graphs both 
functions and data to a resolution of 80 
by 50 points, with automatic scaling 
and labeling of the axes; BARPLOT 
produces horizontal and vertical, 
segmented and labeled bar graphs; 
LETTER displays messages in large 
block letters, using any alphanumeric 
or special character on the PET 
keyboard; and DOODLER can be used 
to create arbitrary screen patterns and 
save them on cassette or in a BASIC 



ELECTRIC PAINTBRUSH by Ken 
Anderson for 4K Level land IITRS-80s: 
Create dazzling real time graphics 
displays at speeds far beyond BASIC, 
by writing 'programs' consisting of 
simple graphics commands for a 
machine language interpreter. 
Commands let you draw lines, turn 
corners, change white to black, repeat 
previous steps, or call other programs. 
The ELECTRIC PAINTBRUSH manual 
shows you how to create a variety of 
fascinating artistic patterns including 
the one pictured. Show your friends 
some special effects they've never 
seen on a TV screen! $14.95 



program $14.95 

WHERE TO GET IT: Look for the Personal Software^ display rack at your local computer store. For the name and address of the dealer 
nearest you, call Personal Software at (408) 745-7841. If you don't have a dealer nearby, you can call or mail us your order with your check, 
money order or VISAIMaster Charge card number. For a free catalog, ask your dealer or use the reader service card at the back of this 
magazine. 



PERSONAL SOFTWARE INC. 

592 WEDDELL DR. • SUNNYVALE, CA 94086 



Circle 302 on inquiry card. 



BYTE September 1979 53 



Listing 


2 continued from page 52: 


22IE 


8D 


00 


17 


STAB PORT-A XOR IN COLUMN 


2221 








I***«************P0RI-B*** : t********* : »***2 


2221 


A5 


2C 




LDA PORT-LIGHT 


2223 


18 






CLC 


2224 


4? 


80 




ADCfi 80 XTOGGLE PL FLAG BIT 


2224 


B5 


2C 




STA PORT-LIGHT 


2228 


2? 


80 




ANDtt 80 


222A 


4A 


4A 




LSK LSK XSET X UR Y AXIS ANH 


222C 


8D 


02 


17 


S1A0 F'ORT-B XXENABLE LEDS 


222F 








XXXXZXXXXXXZXXXXXXXXXXXZXXXXZXXXXXXXXXXXXXXXX 


222F 








XXXXXXX DID STATUS OF SQUARE CHAN6ET XXXXXXX 


222F 








XXXXXXl IF SO RECORD THE CHANGE XXXXX1X 


222F 








xxxxxxxxxxxxxxxxzxxxxxxxxxxxxxxxixxzzxxzxzxzx 


222F 








J*** + ***********REA[I R0U******«***«*****Z 


222F 


A5 


2D 




LDA PORT-SQUARE 


2231 


2? 


30 




ANim 30 


2233 


4A 


4A 




LSR LSR 


2235 


4A 


4A 




LSR LSR 


2237 


AA 






l TAX 


2238 


65 


B7 




I LDAX MASK-TABLE 


223A 


2D 


02 


17 


AND* PORT-B 


223D 








l***********CHECK FOR CHANGES************ 


223D 


DO 


04 




l IF ZERO THEN 


223F 


A5 


34 




LDA TUP-CLEAR-DOUN XSQUARE OCCUPIED... 


2241 


10 


10 




BPL NEXT-SQUARE XANB IN TABLE. 


2243 


30 






BHI 


2244 


04 






ELSE 


2245 


A5 


34 




LDA TUP-CLEAR-DOUN ZSQUARE EHPTY... 


2247 


30 


OA 




BHI NEXT-SQUARE ZXAND NOT IN TABLE 


224? 








ENDELSE 


224? 








X**««»**F0UND A CHANGE, RECORD IT*******X 


2249 


85 


35 




STA UP-CLEAR-DOUN 


224B 


A5 


32 




LDA TCHANGING-SQUARE 


224D 


85 


27 




STA CHANGING -SQUARE 


224F 


A5 


31 




LDA TCHANGING-PIECE 


2251 


85 


28 




STA CHANGING-PIECE 


2253 








ZZXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXZXXXXZXXXXXXXZX 


2253 








XXXXXXXCHECK NEXT SQUARE OR RETURN IF ALL DONEXXXXXX 


2253 








XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXZXXXZXXXXXXXX 


2253 


E6 


32 




NEXT-SQUARE: INC TCHANGING-SQUARE XADD ONE TO 


2255 


A? 


08 




LDAH 08 XXTCHANGING-SBUARE 


2257 


25 


32 




AND TCHANGIN6-SQUARE 


225? 


OA 






! ASL 


225A 


IB 






CLC 


225B 


45 


32 




ADC TCHANGING-SQUARE XADD "CARRY" 


225D 


29 


77 




AND* 77 XHASK OUT GARBAGE 


225F 


85 


32 




S1A TCHANGING-SQUARE 


2241 


F0 


03 




BEQ RETURN 


2243 


4C 






JHP XXXGO CHECK NEXT SQUARE 


2244 




B5 


21 


ENDLOOP 


2244 


A? 


00 




RETURN: LDA* 00 


2248 


85 


2E 




STA SPEAKER-FLAG 


224A 


EE 


02 


17 


INC? PORT-B 


224D 


AS 


35 




LDA UP-CLEAR-DOUN 


224F 


40 






RTS 


2270 










END OF 


ASSEMBLY 





upon which the new piece was set 
down. Modify the first byte by typing 
in the correct name of the new piece. 
If the piece has been previously cap- 
tured, it may be added to the piece 
table by typing the + key. 

To change sides (Black to White, or 
vice versa), type the E key. A count- 
down will be initiated. Do not change 



sides before the opening move of the 
game; the King, Queen, and other 
pieces could become incorrectly 
reversed. 

Conclusion 

Although it may require a lot of 
solder, building the hardware is 
neither hard nor exacting work. As 



with most projects, if it doesn't work 
the first time the problem can usually 
be traced to an incorrect program, 
faulty wiring, or bad integrated cir- 
cuits. In this particular project, the 
program is already written, the 
wiring is easy to check, and there are 
only 2 integrated circuits. 

The electronic chessboard can, of 
course, be used for activities other 
than chess. Almost any game that is 
played with an X,Y type grid can be 
played by the computer, among 
these: checkers, tic-tac-toe, and nim. 

I have found that the chessboard 
interface makes playing chess with 
the KIM-1 much more enjoyable. 
Even if you lose the chess game, the 
method of playing is sure to be im- 
pressive. ■ 

Editor's Note 

The program described in this arti- 
cle was designed to be "foolproof" for 
the beginning chess player. The 
countdown period for changing a 
move will greatly ease the frustration 
often experienced by players of com- 
puter games, the sinking feeling of 
"Oh no, I didn't mean that, and 
there's no way to take back the 
move!" More programmers should 
pay such attention to the user inter- 
face of their systems. 

More experienced chess players 
generally abide by the following rule: 
a piece once touched by the player 
must be moved, and an opponent's 
piece once touched must be captured. 
Such users would probably wish to 
delete the countdown period to speed 
the progress of the game. 

An electronic chessboard operating 
in a similar fashion appeared in the 
article "Chess 4.7 versus David Levy" 
by J R Douglas (December 1978 
BYTE, page 84). That board, con- 
structed by Dr David Cahlander of 
Control Data Corp, uses 1 light emit- 
ting diode (LED) in each square of the 
chessboard to indicate the computer's 
move, and uses magnetic switches 
placed under the squares which are 
activated by the metal weights in the 
pieces. Controlled by a 6800 micro- 
processor, Cahlander's board trans- 
mits and receives moves to and from 
a remote computer on which the 
Chess 4.7 program runs... RSS 



54 September 1979 © BYTE Publications Inc 



page 



Precut Wire Wrap Wire 

PRECUT WIRE SAVES TIME AND COSTS LESS THAN WIRE ON SPOOLS 




Kynar precut wire. All lengths are overall, including 1 " strip on each end. Colors and lengths 
cannot be mixed for quantity pricing. All sizes listed are in stock for immediate shipment. 
Other lengths available. Choose from colors: Red, Blue, Yellow, Orange, Black, White, Green 
and Violet. One inch tubes are available at 50<t each. State second choice on colors when 
possible. 

Length 100 500 1,000 Length 100 500 1,000 



2.5 

3 

3.5 

4 

4.5 
5 

5.5 
6 



nches 



1.04 


2.98 


5.16 


1.08 


3.22 


5.65 


1.13 


3.46 


6.14 


1.18 


3.70 


6.62 


1.23 


3.95 


7.12 


1.28 


4.20 


7.61 


1.32 


4.48 


8.10 


1.37 


4.72 


8.59 



6.5 inches 


1.60 


5.37 


9.84 


7 


1.66 


5.63 


10.37 


7.5 


1.73 


5.89 


10.91 


8 


1.78 


6.15 


11.44 


8.5 


1.82 


6.41 


11.97 


9 


1.87 


6.76 


12.51 


9.5 


1.92 


6.93 


13.04 


10 


1.99 


7.26 


13.57 



ffllW 



Kit #1 $7.95 

Less than 2.7C/M. (#30) 



250 
250 
100 



3" 

3Vr" 

4" 



100 
100 
100 



4V 2 ' 

5" 

6" 



Hill 

111' 



Kit #2 $19.95 

Less than 2C/ft. (#30) 



250 
500 
500 
500 
250 



2V," 

3" 

3VS" 

4" 
4'/?" 



250 
100 
250 
100 
100 



5" 

5V ? " 

6" 

6Vi" 

7" 



*m m 



Kit #3 

Less than 1.7C/H. (#30) 



500 
500 
500 
500 



3" 

4" 



500 
500 
500 
500 



4'/ 2 " 
5" 
5V?" 
6" 



AVAILABLE AT SELECTED LOCAL DISTRIBUTORS 

Circle 298 on inquiry card. 

135 E. Chestnut Street 






Kit #4 $44.95 

Less than 1.6C/H. (#30) 



1000 
1000 
1000 
1000 



2'/?" 
3" 
3'//' 
4" 



1000 
1000 
1000 
1000 



4'/ 2 " 
5" 
5" 
6" 



#30 Spools 
1-4 



5-9 10+ 



50 ft. 

100 ft. 

250 ft. 

500 ft. 

1000 ft. 



1.75 
3.00 
4.75 
8.50 
14.50 



1.60 
2.75 
4.50 
8.00 
12.50 



1.40 
2.50 
4.25 
7.50 
10.50 



ORDERING INFORMATION 



page 



• Orders under $25, add $2 handling 

• Blue Label or First Class, add $1 (up to 3 lbs.) 

• CODs VISA & MC orders will be charged shipping 

• Most orders shipped next day. 



5A, Monrovia, California 91016 Phone (213) 357-5005 



I MicroPro 



MicroPro International Corporation 

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change aPl>. t0 P„„„ ceS Ki[y to re" 






qn £3Wfc umecesf 
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print image 
printout. 



a cp/k compatible, s 

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additional < 



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stored on diskette. Featm 
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Video Editing: a portion of n, ^ 

always shown c^n fira^miftte" *« n 9 «t«ed or corrected i- 



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o change the margins or line 
titled or vice versa, or to 






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Dealer/Distributor/O.E.M. Inquires Invited 



56 BYTE September 1979 



MICROPRO INTERNATIONAL CORPORATION 
1299 4th Street, San Rafael, California 94901 
Telephone (41 5) 457-8990 Telex 340388 




HcroPro International 

fi': av^J mIi • ;|UK. iifiiiiiy ; ^: ^ ■>■—,,■ , .^,>ui ^ an ( ount on, no 



MicudPbo 



1299 Fourth Street, San Rafael, California 94901 • Telephone (415) 457-8990 • Telex 340388 



Programming Ouickies 



A Similarity Comparator for Strings 



T C O'Haver 

Professor 

Dept of Chemistry 

University of Maryland 

College Park MD 20742 



The trouble with computers is that 
they have no common sense. If a 
computer is directed to search a file 
looking for a particular string of 
characters, a simple typographical 
error will cause the computer to 
report that no match has been found; 
even though there was something 
very close in the file. The statement 
"If A$ = B$ THEN. . . " is taken 
literally by the computer; even the 
slightest difference is not tolerated. 

Wouldn't it be better if a computer, 
finding no exact match, would report 
the best match, or the 5 best matches 
listed in order of closeness of match? 
To do this, a routine is needed that 
returns a quantitative estimate of the 
similarity between 2 strings. That is 
what the routine illustrated here does; 
it computes a similarity index on a 
scale of thru 100 percent. 

Listing 1 gives a BASIC string com- 
parator program. The heart of the 
program is in lines 100 thru 290; lines 
10 thru 90 are there only to allow the 
routine to be demonstrated with 2 
manually input strings. The funda- 
mental idea is simple: each character 
in one string is compared to each 
character in the other string. This is 
done so that groups of characters that 
match are weighted more heavily 
than the same number of matches of 
individual characters. This allows, 
for example, "POOL" and "POOR" 
to be rated more nearly equal than 
"POOL" and "POLO", even though 
the latter 2 strings have more 
characters in common. 



10 


LETT = 


20 


LETP = 3 


30 


PRINT "FIRST WORD" ; 


40 


INPUT A$ 


50 


LETA=LEN(A$) 


60 


PRINT "SECOND WORD" ; 


70 


INPUT B$ 


75 


IF A$ = B$ THEN PRINT "EXACT MATCH 


80 


LETB=LEN(B$) 


90 


IFA>B THEN LETB = A 


100 


FOR M = 1 TO B 


110 


LETC = 


120 


FOR I = 1 TO M 


130 


LETK$=MID$(A$, B-M + 1,1) 


140 


LETL$=MID$(B$,I,1) 


150 


IF K$ = L$THEN LETC=C+1 


160 


NEXT I 


170 


LETC = C!P 


180 


LETT = T + C 


190 


NEXTM 


200 


FOR M = B+1 TO 2*B-1 


210 


LET C = 


220 


FOR 1 = 1 T0 2*B-M 


230 


LETK$=MID$(A$,I,1) 


240 


LETL$=MID$(B$,M-B+I,1) 


250 


IFK$ = L$THEN LETC = C+1 


260 


NEXT I 


270 


LETC = CtP 


280 


LETT = T + C 


290 


NEXTM 


300 


LETS=100*T/BtP 


310 


PRINT S;"%" 


320 


LETT = 


330 


GOTO 70 


340 


END 



Listing 1: Listing of the similarity comparator program in Ohio Scientific Instruments 
8 K BASIC (a Microsoft interpreter). The up arrow indicates exponentiation. 



58 September 1979 © BYTE Publications Inc 



What makes the Microtek Printer 
so different? Nothing! 




EXCEPT. . . . 



THE PRICE: $750 (with parallel interface) 
THE PERFORMANCE: 



• 80 or 1 20 columns (software selectable) 

• Plain paper 

• Pin Feed 

• Double width printing 

• 1 25 characters per second, 70 lines per minute 
nominal throughput 

• 9x7 Matrix (80 columns/line), 7x7 Matrix (1 20 
columns/line) 



• Vertical Format Unit 

• 96-character ASCII (upper and lower case) 

• Forms width continuously adjustable between 
4.5 inches and 9.5 inches (including sprocket 
margins) 

• Parallel (Centronics type) interface standard. 
Serial (RS-232) and IEEE-488 interfaces 
available 



To: MICROTEK, Inc., 7844 Convoy Court, San Diego, California 921 1 1 
□ Send me more information. 



(714) 278-0633 



□ Send me a printer with: 

□ Parallel interface <w $750. 

□ Check or Money Order enclosed. 



□ Serial interface ® $835. 



□ IEEE-488 interface ® $895 



name (please print) 



□ Charge my VISA card. □ Charge my Master Charge card. 



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cardholder's signature 



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Add $15.00 for packaging & shipping. 



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I 

BYTE September 1979 59 



Circle 209 on inquiry card. 



The weighting of groups of 
characters is controlled by the 
variable P defined in line 20. If P is set 
to a value of 1, there is no special 
weighting of groups; only the total 
number of characters in common be- 
tween the 2 strings is counted. If P is 
set greater than 1, groups are 
weighted more heavily, proportional 
to the value of P. If P is too large, 
however, all but the very closest 
matches result in low similarity in- 
dex. A value of P = 3 is a good com- 
promise. 

Line 300 scales the index to within a 
range of approximately thru 100 
percent. Two strings with no com- 
mon characters give percent simi- 
larity, while 2 identical strings give 
100 percent similarity. Sometimes 2 
nonidentical, but very similar, strings 
with many repeated letters (eg: 
"AAAAA" versus 'AAA") will give 
100 percent or greater than 100 per- 
cent similarity. This is seldom a pro- 
blem with practical strings. 

Strings of any type can be com- 
pared: names, addresses, numerals, 
or even strings containing spaces and 
punctuation. Long strings take a long 
time to compare, up to several 
seconds. An assembly language ver- 
sion should run much faster, if speed 
is important in your application. 

The routine in listing 1 is written in 
Ohio Scientific Instruments 8 K 
BASIC, Version 1, and was run on a 
Challenger II system. The syntax of 
the string functions, particularly 
MID$, may be different in other 
BASICs. However, it should be com- 
patible with most of the other BASIC 
interpreters which were developed by 
Microsoft. The program also runs 
without modification on an 8 K 
PET.H 



Sample Run Comments 

RUN 

FIRST WORD? POOL 
SECOND WORD? POOL 
EXACT MATCH 

103.1% 
?POOR 

45.3% 
?COOL 

45.3% 
? POO 

45.3% 
? POLO 

28.1% 
? LOOP 

18.7% 
?PAIL 

12.5% 
? POOL ROOM 

10.4% 
? MAIL ROOM 

1.5% 
? PO/OL 

14.4% 
?0000 

40.6% 

OK 

RUN 

FIRST WORD? T.C. O'HAVER 710 HILLSBORO DR. SILVER SPRING MD. 

SECOND WORD? TOM O'HAVER 710 HILLSBORO DR. SILVER SPRING MD. 

82.9% 
? R.D. O'HAVER 710 HILLSBOROUGH RD. SILVER SPRINGS FL. 

10.3% 
? 

OK 



>100% because of double letter 
3 letter pattern "POO" matches. 

Still a 3 letter pattern. 

Same match, because nonmatching 
characters do not count. 

Two 2 letter matches, "PO" and 
"OL", do not count as much 
as one 3 letter match. 

Only 2 isolated letters. 



Presence of extra random 
character reduces match. 
Repeated letters result 
in unexpectedly high match. 



Listing 2: A sample run of the program, with comments explaining the value of similar- 
ity assigned. 



Note: We entered this program into an Apple II computer 
using the Applesoft floating point BASIC. It ran without 
modification. The exact values of similarity computed 
did sometimes differ from those given in the sample run, 
but only in the fourth significant digit and beyond . . . 
RSS 



E, 



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Analog to Digital Conversion System for the KIM Computer 



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n«asurer and control tne world around 
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so you can hooK up Joysticks* pots* or 
whatever approF-riate sensors you have. 

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snd 255 < 20 millivolts per count). 
Conversion time is 100 microsconds. 

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60 



September 1979 © BYTE Publications Inc 



Circle 76 on inquiry card. 



Unclassified Ads 



Unclassified Policy 

Readers who are soliciting or giving ad- 
vice, or who have equipment to buy, sell or 
swap should send in a clearly typed notice 
to that effect. To be considered for publi- 
cation, an advertisement must be clearly 
noncommercial, typed double spaced on 
plain white paper, contain 75 words or less, 
and include complete name and address 
information. 

These notices are free of charge and will 
be printed one time only on a space 
available basis. Notices can be accepted 
from individuals or bona fide computer 
users clubs only. We can engage in no 
correspondence on these and your confir- 
mation of placement is appearance in an 
issue of BYTE. 

Please note that it may take three or four 
months for an ad to appear in the 
magazine. 



FOR SALE: Cromemco 16 K programmable memory. 4 
MHz. bank select. $400 cr best offer. Will Aokel, 4860 Rolan- 
do CI #22. San Diego CA 92115, (714)287-6823. 

EXCHANGE IDEAS: I want to talk and write to microcom- 
puter users who are interested in programming for farm 
operations, especially in the area of Southwest Kansas, 
Southeastern Colorado and the Oklahoma Panhandle. I am 
using an Apple II. Van Lynn Floyd, RR #1 POB 94, Johnson 
KS 67855. 

FOR SALE: OSI 65 V system, including: 6502 processor 
board. 16 K memory board; video interface board; power 
supply and case. SwTPC keyboard; single drive lloppy disk, 
floppy disk interface board; lloppy disk power supply and 
case; all documentation (OSI and fvlOS technology); includes 
BASIC. Assembler, Disassembler and extended monitor. All 
assembled, tested and running well. $1800 or best offer. C 
Gum, 757 E Main St W-304 Wiss Apt. Lansdale PA 19446. 
(215)855-4182. 

WANTED: Programs (games, graphics or just unusual pro- 
grams) in BASIC. Hope to establish a no cost program library 
in the near future. All material written or cassette (cassettes 
in TRS-80 Level 2 only) returned. Richard G Ginder, 509 
Southern Hills Dr, Hot Springs AR 71901. 

FOR SALE: SOL-20 computer by Processor Technology with 
32 K. video display, cassette mass storage, Extended BASIC, 
IBM Seleclric lypewriter/printer, text editing and other soft- 
ware, complete documentation and manuals. Ideal for small 
business software development, 1.5 years old, $2500. 
Middleton Associates. 980 Yonge St Ste 404. Toronto 
Ontario. CANADA M4W 2J9. (416) 961-5136. 

FOR SALE: S-100 bus system. Cromemco Z80 processor. 
Byte-8 mainframe, TDL system monitor board, ACT-I 
keyboard, North Star disk and software, two 16 K static pro- 
grammable memory (250 ns). less 8 K of chips. Panasonic 
video monitor. Up. tested and running. For more details of 
system, send SASE or phone (206) 456-2466 after 5 PM. 
Donald A Coulter, 8002 Mountain-Aire Loop SE, Olympia WA 
98503. 

FOR SALE: Sencore Model PS163 dual trace scope in new 
condition. Used less than 20 hours. Complete with two 
probes. Faclory price $895, will offer for $350. Also, Sencore 
Model PS148 single trace scope/vectorscope, still in faclory 
carton Sacrifice, $195. R Conde. 11 Sugarbush Ln. Coram 
NY 11727, (516)928-4849. 

FOR SALE: Digital Group TVC64 16 line 64 character upper 
and lower case and Greek with plug $125; COSMAC ELF with 
complete address light emitting diodes, hexadecimal thumb- 
wheels, audio output, automatic stepping and other features 
$110; hexadecimal keyboard for ELF $30; Mikos mother 
board with 12 100 pin connectors in place $75; Proko PTR-II 
optical paper tape reader $50. Bert Thiel.159 W Main St, 
Frostburg MD 21532, (301) 689-8608 weekends and even- 
ings. ■ 



Circle 335 on inquiry card. 





Whynol 

kill two birds 

with one stone? 

If you have an Apple* and you want to interface it with 
parallel and serial devices, we have a board for 
you that will do both. It's the AIO.™ 

Serial Interface. 

The RS-232 standard assures maximum compat- 
ibility with a variety of serial devices. For ex- 
ample, with the AIO you can connect your Apple* 
to a video terminal to get 80 characters per line 
instead of 40, a modem to use time-sharing 
services, or a printer for hard copy. The 
serial interface is software programmable, 
features three handshaking lines, and 
includes a rotary switch to select from 
7 standard baud rates. On-board firm- 
ware provides a powerful driver 
routine so you won't need to write any 
software to utilize the interface. 

Parallel Interface. 

This interface can be used to connect your 
Apple* to a variety of parallel printers. The 
programmable I/O ports have enough lines 
to handle two printers simultaneously with 
handshaking control. The users manual 
includes a software listing for controlling 
parallel printers or, if you prefer, a par- 
allel driver routine is available in firm- 
ware as an option. And printing is 
only one application for this general 
purpose parallel interface. 

Two boards in one. 

The AIO is the only board on the market that can interface the Apple 
to both serial and parallel devices. It can even do both at the same 
time. That's the kind of innovative design and solid value that's been 
going into SSM products since the beginning of personal computing. 
The price, including PROMs and cables, is $135 in kit form, or S175 
assembled and tested. See the AIO at your local computer 
store or contact us for more information. 

2116 Walsh Avenue 

Santa Clara, California 95050 

(408)246-2707 





'Apple is a 
TM of Apple 
Computers, 
Inc. 



Some Musings 
on Hardware Design 



Clayton Ellis 

Rt 4, POB 86 

Montrose PA 18801 



The purpose of this article is to acquaint 
the reader with some of the more interesting 
types of transistor-transistor logic (TTL) 
integrated circuits, the ease with which logic 
design can be accomplished, and to offer a 
few design considerations and trouble- 
shooting hints to stimulate the homebrew 
use of digital logic. 

Taking the topics in the above order, we 
start with a look at some of the more com- 
plex types of TTL chips in the "74xx" 
series. (We will ignore simple gates for the 
most part.) An example is the 7442. This 
integrated circuit is a binary coded decimal 
(sometimes called BCD) to decimal decoder. 
What this means is that the circuit will 
decode 1 line out of 10 based on a 4 bit 
binary code. Figure 1 shows the pin con- 
nections. Regardless of what it is called, 
it works like this: pins 12 thru 15 are a 4 bit 
binary input, pin 1 5 being the 1 's bit (bit 0), 
14 the 2's bit (bit 1), 13 the 4's bit (bit 2), 
and 1 2 the 8's bit (bit 3). Pins 1 thru 7 and 9 
thru 11 comprise the output pins, each pin 
staying high (logic 1 or a higher level voltage 
of about 3 to 5 V) unless the corresponding 
binary code is applied to the input. For 
example, let's say that pins 12 thru 15 are 
0101. In other words, 12 is at a logical low 
(about V); 13 is at a logical high level 



► 5V 
A 









16 










Vcc 


O 
1 
2 


l 


15 


A 


7442 


2 




3 






14 


B 




3 
4 


4 






5 








5 


6 






13 


C 




6 


7 












7 
8 
9 


9 


12 


D 




10 






1 1 






GND 





a 



(above about 3 V, less than 5 V), etc. In this 
case, pin 6 (indicating a decimal 5) would be 
at a logical low level (about V). All other 
pins relating to decimal output numbers 
would be at a logical high level. Note that 
only one output pin will be low at any given 
time, corresponding to the binary value of 
the input lines. "Ahh," you might ask, 
"what if the input pins are at some binary 
value other than thru 91" The answer is 
easy; this constitutes an invalid input, and all 
output pins will stay high. Only valid deci- 
mal values will select an output pin. 

Now let's move on to a module similar to 
the 7442, the 74154. Referring to figure 2, 
the first apparent difference is the larger 
number of pins on the 74154. This inte- 
grated circuit is a 4 line to 16 line decoder. 
Its operation is the same as the 7442, with 
but two exceptions: there are now 16 valid 
output lines, and provision is made to allow 



24 



ADDRESS 

LINES 



23 



22 



GATE 

INPUTS \ 19 





Vcc 






A 


74154 


O 
1 


2 






2 


3 


8 




3 


4 






4 


5 


C 




5 


6 






6 


_7 


D 




7 


8 






8 


9 






9 


IP 






10 


II 






1 1 


13 






12 


14 


Gl 




13 


15 


G2 




14 


16 




GND 


15 


17 






12 








n 


7 







\0UTPUTS 



Figure J: Pin connections for a 7442 TTL 
binary coded decimal to decimal converter. 



Figure 2: Pin connections for a 74154 TTL 
4 line to 16 line decoder. 



62 September 1979 © BYTE Publications Inc 




DATA 
' SELECT 



STROBE 



Figure 3: Pin connections for a 74750 TTL 
1 of 16 line data selector. 



two extra inputs to gate the individual line 
selected. Pins 18 and 19 perform this gating 
function. An example of use of this extra 
gating feature might look like this: pins 20 
thru 23 might contain the binary equivalent 
of a decimal 14, pin 19 being low and pin 18 
alternating from high to low (a periodic 
clock pulse.) The end result is that pin 16 
(corresponding to line 14) will also periodi- 
cally alternate high and low in following the 
signal on pin 1 8. The data at pin 18 is trans- 
ferred to pin 14. If the binary code on pins 
20 thru 23 were now changed to a decimal 
7, then line 7 (pin 8) would follow the data 
on pin 18. We select one of 16 outputs for a 
signal applied to the gates. Now, if we could 
just have a binary controlled switch to select 
1 of 16 inputs. Let's look at the 74150. 
Figure 3 shows the pinout of this one. 
This time there are 21 input pins and only 1 
output pin. 

Let's see how this one works. Binary 
input is on the 4 lines of pins 1 1 and 1 3 thru 
15. Let's say a binary value of 12 is present. 
This selects the number 12 input line (pin 
19) and transfers the level of this line, be it 
steady, high, low or some alternating clock 
signal, to pin 10, the output line. Notice, 
though, that in order for the data to be 
transferred, pin 9 (the strobe input) also 
must be low. A high level on the strobe 
input prevents any data transfer from any 
input. This feature is used to allow data 
transfer only at selected intervals, such as 




The way you 
check line-by-line with 
an A P Intra-Switch or 
Intra-Connector. 

You plug your Intra-Switch in-line 
with standard socket connectors, 
and instantly you've got a separate, 
independent on-off switch for each 
and every line in your flat ribbon 
cable. To switch, you nudge with a 
pencil point. It's that quick. 

Imagine how much time and 
trouble Intra-Switch will save you in 
your diagnostic and quality testing, 
your programming and selective 
line inhibiting. 

Or, plug in your Intra-Connector 
(see box) the same way, and you 
have an extra set of male contacts 




at right angles. Instant line-by-line 
probeability— and an easy way to 
tap your system and daisy chain it 
into new areas. 

Both Intra-Connectors and Intra- 
Switches come in 20, 26, 34, 40 and 
50-contact models. 

Where? At your nearby A P deal- 
er. Where's that? Phone (toll-free) 
800-321-9668. And ask for the com- 
plete A P catalog, The Faster and 
Easier Book. 




AP PRODUCTS 
INCORPORATED 

Box 110D • 72 Corwin Drive 
Painesville, Ohio 44077 
Tel. 216/354-2101 
TWX: 810-425-2250 



Faster and Easier is what we're all about. 



Circle 10 on inquiry card. 



September 1979 © BYTE Publications Inc 63 




CDMPHCT 
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Forms generates record descriptions 
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and then automatically creates the 
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This text is held on diskette as COPY 
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Standard Compiler conforms to ANSI 74 
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microprocessors, making CIS COBOL a very attractive proposition for 
OEMs. 



MICRO FOCUS 

MICRO FOCUS LTD. 58 Acacia Rd, St. Johns Wood, London NWB 6AG 
Telephone: 01-722 8843 Telex: 28536 MICROF G 
•CP/M is a trademark ot Digital Research 



64 BYTE September 1979 



Circle 210 on inquiry card. 



Figure 4: A data selector 
to sample each of 16 lines 
sequentially. It looks good, 
but it doesn't work. A 
neglected inversion in logic 
levels and thinking is the 
demon. 




I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 
74154 Vcc 

A B C D GND 



o- 



23 



12 



22 



21 



20 



12 



► 5V 



rh 



+ 5V 



Figure 5: Another approach to the problem 
in figure 4. This approach has a much lower 
parts count, so it is much easier to wire and 
it works. 



0A QB QC 
B 7493A 

A(CLOCK) „ 



QD 
Vcc 



m 

when the input would contain valid data, or 
when the output is useful only at specific 
intervals. 

Now that we have taken a look at a few 
of the more involved logic blocks, let's look 
at how easy it is to design the somewhat 
more complicated circuits using the simple 
TTL blocks in conjunction with one or more 
of the above type of logic blocks. 

If we want to build a sequencing device 
to look at a number of incoming lines, and 
if we are to use a given clock signal to coor- 
dinate all this, we can use the logic circuit 
in figure 4. A very simple and straight- 
forward circuit, right? Not quite. Let's take 
a second look. All the inputs but the one 
selected by the 74154 are going to be en- 
abled at one time. The selected pin goes low, 
remember? By this time, if not before, you 
probably recalled the look we just took at 
the 74150 and are wondering why we did 
not use it. Figure 5 shows the circuit using 
the 74150. The foregoing just illustrates a 
good point (and one to keep in mind when- 
ever you undertake any logic design). There 



o- 

o- 

O- 
O- 
O- 



o- 
o- 



Vcc 
74I50 



OUT 



C^ 



-o 



1 



OA QB 0C 0D 
B V 

749 3 A 

A(CLOCK) 

Rl R2 GND 



September 1979 © BYTE Publications lnc 65 



Get circuit requirements down on paper in block form. 
Break each block down into required logic. 

Use the most integrated block available for each function as in the example of 
figure 5 unless the cost of such a module is much higher than two or possibly 
three less intricate ones. 

Don't go overboard with smaller blocks. This increases the density and complexity 
of interconnection, greatly increases the chances of errors and reduces system 
reliability. 

Cross-check all designs, as you may have redundantly developed the same signal 
line. Sometimes most of one segment of a circuit can be eliminated with an inver- 
ter or small amount of additional gating. 

If possible, have a friend familiar with digital logic go over the layout. Your friend 
can sometimes suggest circuit reductions that you missed simply because you 
were thinking one way while your friend used a different approach. The same 
review may even spot an error in the logic. With all those inversions, gating, etc, it 
is easy to do. Spotting an error at this stage can save hours at the breadboard stage. 



Table 1: Approach to 
finding the simplest logic 
circuit for a given function. 



are many ways to accomplish a specific func- 
tion. So many, in fact, that large companies 
who do digital logic design in large quantities 
invariably use some form of computer aided 
logic design. The homebrew enthusiast ob- 
viously can't go that far, but the approach 
summarized in table 1 usually works fairly 
well. 

Timing 

Another good point to keep in mind is to 
think time (not in terms of how long it takes 
to design a circuit, or build it, but time rela- 
tionships in the circuitry itself). This brings 



us back to a term, clock, that we have been 
using freely up to now. We all know that a 
clock is merely a line, usually derived from a 
square wave oscillator, right? This line is 
then used to coordinate all necessary gating, 
shifting, setting and resetting, etc, that goes 
on within the circuitry itself, right? Well, 
that is part of it, but who said it had to be a 
single line? Some computers use a number 
of clock lines, perhaps as many as 8 or 10. 
The only thing these multiple clock lines 
have in common is that they are usually all 
derived from the same oscillator and may 
be individually gated on or off, counted, 
decoded or subjected to any other valid logic 
manipulation. 

Figure 6 shows a typical clock circuit 
detailing some of these practices. As you 
can readily see, almost any combination of 
clock times can be selected, and the flip 
flops can be extended as far as needed to 
select a single clock pulse or a repetitive 
series of clock pulses. The point to remem- 
ber is that all pulses are derived from the 
same clock and each pulse on any line will 
be of the same duration as any other clock 
pulse. The single clock pulse shown on 
line C of the timing chart in figure 6 will 
start at the same time as the fourth clock 



TOGGLE FLIP FLOPS DIVIDE FREQUENCY BY 2 



Figure 6: A hypothetical 
clock circuit to give two 
different phases (lines A 
and B) at two different 
repetition rates. Lines A 
and B are at 1 j2 the clock 
rate. Line C is at 1/8 the 
clock rate with the same 
pulse duration. 



-^>c— [u>c- 



T Q 

FF I 



T 

FF2 



{> 



T Q 

FF3 



T 

FF4 






^>A 



Ob 



^y 



-Oc 



CLOCK 



~L 

~L 

~L 



r 



n 



CLOCK* FFI 



_TL 



CLOCK.FFI 



CLOCK'FFI • FF2 "FF3 



66 September 1979 © BYTE Publications Inc 



pulse on line A, and the duration will be 
identical. 

There is one fly in the ointment at this 
point. I just noted that the two clock pulses 
would start at the exact same time. That is 
not quite true, however, and depending on 
how fast the clock is running, and exactly 
what is being gated, this may or may not be 
a problem. 

In an actual circuit, the clock pulse on 
line A would go positive slightly ahead of 
the pulse on line C. This is due to the delay 
(called propagation delay) across each flip 
flop encountered by the leading edge of the 
pulse. This delay is on the order of nano- 
seconds for each gate encountered. Let us 
assume an arbitrary 5 ns delay for each gate. 
Then the delay from the input of FF1 to the 
output of the AND gate driving line A would 
be 10 ns. This is 5 ns for FF1 and 5 ns for 
the AND gate. The delay from the input to 
FF1 to the output of the AND gate driving 
line C would be not 10 ns, but 20 ns: 5 ns 
for each of the three flip flops and 5 ns for 
the AND gate. The pulse on line C would 
actually start 10 ns after the one of line A. 
This will also make a difference in the dura- 
tion of the pulse on each line; as the plus 
level arriving later than the clock pulse at 
the input to the AND gate determines when 
the output of the AND gate goes positive. 
However, the trailing edge of the clock pulse 
input determines when the AND gate output 
goes negative. 

This, in effect, shortens the duration of 
the pulse on the output line by a time (in 
nanoseconds) determined by the various 
propagation delays. If the clock frequency 
of the circuit is on the order of tens or hun- 
dreds of kilohertz, then a delay of tens of 



nanoseconds would be of little consequence; 
but if the clock frequency of the circuit is 
something like 20 or 25 MHz, the delay can 
become a thorn in the side of the designer. 
This holds true for all data and control lines 
we well as clock lines. 

This propagation delay can be used to an 
advantage too. Figure 7 illustrates using this 
delay to generate a narrow pulse. Here the 
positive going (leading) edge of the input is 
applied to an AND gate, but the negative 
going (trailing) edge of the inverted version 
applied to the other leg of the AND gate is 
delayed by the total of the propagation 
delay across the three inverter blocks. The 
resultant output is a narrow pulse equal in 
duration to the delay across the inverters. 
This method of generating a pulse is only 
useful in cases where we don't care exactly 
how long the pulse lasts since gates and 
inverters are subject to manufacturing 
variations. 

To satisfy the rather picky individual or 
very high speed circuit, I have to say also 
that the output pulse is not only derived 
from the inverter delay, but is delayed from 
the leading edge of the original pulse by the 
amount of the delay across the AND gate 
itself. Figure 8 illustrates this. The short de- 
lays shown on waveform C are due to the 
AND gate propagation delay. For most situa- 
tions, this is carrying propagation delay 
accounting to extremes, but in certain high 
speed circuits each delay may have to be 
accounted for. If 20 or 30 gates are involved, 
the cumulative effects add up rather fast. 

Also to be considered is the capacitive 
effect of the interconnection lines: the dis- 
tributed and stray capacitance which are in 
parallel with the output of each gate add 
slightly to delay times. It takes a finite 
amount of time to charge this capacitance at 




Figure 7: A pulse generator for nanosecond 
range pulses. Pulse length Is determined by 
the propagation time through the gates 
between the input and point B. More sophis- 
ticated methods are required if an accurate 
pulse length is required. 



Figure 8: A magnified view of the pulse 
shown in figure 7. The output pulse is de- 
layed by the propagation time of the A ND 
gate. This time varies but is typically about 
10 ns for normal transistor-transistor logic, 
less for the high speed and Schottky version 
and more for the low power integrated 
circuits. 



September 1979 © BYTE Publications Inc 67 



each gate turn on, and the gate will not 
switch until a certain voltage input level is 
reached. All of which leads right into the last 
subject I'd like to touch on. How do you see 
all this in an actual circuit? Believe me when 
I say that it takes a good oscilloscope. To 
have a good display in the tens of nano- 
seconds range, it takes an oscilloscope with 
a bandwidth of at least 60 to 100 MHz. 
Does this mean that anyone without such 
an oscilloscope can't do much with higher 
speed TTL? Not necessarily. Remember we 
said that propagation delay only becomes 
a problem at high speeds and multiple gate 
delays. There are a number of ways around 
this. One is to keep clock frequencies and 



data changes as slow as possible. Don't use 
a fast clock or data encoding just for the 
sake of speed, run it as fast as necessary 
and no faster. If you can tolerate a slow 
clock speed, use it. Another method is to 
try and bring each data line that is to be 
gated with another line through the same 
number of gates as the line it is to be gated 
with. In other words, if one line originates 
at about the same source as another that it 
is to be gated with, but passes through 9 
levels of gating, and the other line passes 
through 3, the delays at high speeds can be 
a problem. This could be compensated for 
by changing the way the lines are gated to 
bring the delays in each line closer to the 



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ComputerLand 

■ WE KNOW SMALL COMPUTERS 



68 September 1979 © BYTE Publications Inc 



Circle 75 on inquiry card. 



same length. Another help in extreme cases 
is to run the line with the lesser number of 
gates through several pairs of inverters. This 
introduces a delay to compensate for the 
delay in the other line. In other words, 
make the faster line wait for the slower one. 
An even better solution is to design your 
circuits "synchronously" so that only one 
clock source ever changes the state of a flip 
flop or memory cell. 

As to seeing these problems on the slower 
oscilloscopes, there are several hints that will 
help. Very little serious work with timing 
relationships can be undertaken without a 
dual trace capability (although a good deal 
can be done otherwise with TTL with just 
a single trace scope). Even with a dual trace 
oscilloscope, the fastest sweep speed may 
not reveal a lot of timing detail if not set up 
correctly and the alternate sweeps may not 
be time correlated without a common syn- 
chronization signal. A number of tests can 
be made with a single trace oscilloscope if it 
has provisions for external synchronization. 

In general, synchronize the oscilloscope 
sweep as far ahead in time as is realistic for 
the signals in question, in order to allow 
time for the sweep to start before the pulse 
actually arrives. It goes without saying that 
the synchronization signal must be common 
to all signals being examined. 



If you still can't see any difference, try 
estimating the approximate delay for each 
line from source to common logic block. 
Most logic handbooks list typical delays for 
integrated circuits. If the problem is in a 
counter circuit of some type which counts 
"up," the count for a given sequence will 
usually be too high in value if delay prob- 
lems are the cause. Rarely will the count of 
an "up" counter be too low, as the usual 
situation is advancing the counter by an ex- 
tra pulse generated by mismatched delays, 
especially if a lot of exclusive ORing is being 
done. The situation where early turn off or 
disabling of the counter causes a missed 
count is quite unlikely, mainly because the 
delay is of a much shorter duration than the 
pulses being counted. 

These problems are all good to be aware 
of, but don't let them deter you from start- 
ing that project you were thinking about. 
You may go a long time before you see one 
of the problems described. Don't let the 
lack of a superb oscilloscope deter you 
either. A lot of very intricate and fast digi- 
tal circuitry is being built every day with 
nothing more than a single trace I MHz AC 
coupled oscilloscope. With a little experi- 
ence, you can tell a great deal about a given 
TTL circuit with one of these inexpensive 
oscilloscopes." 




When no one 
has your floppy disks 
in stock ... 

here's a new 

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The word is Kybe. Because Kybe can ship any model 
floppy disk, data cassette or mag card in only two days. 
You'll get the same high performance products sold by 3M, 
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warranty and inventoried for fast delivery. 

Dealer inquiries invited. 

(800)225-8715 
KYBE 



K 



fi 



KYBE CORPORATION 

132 Calvary Street. Wallham, Mass 02154 
Tel. (617) 8990012. Telex 94-0179 
Offices & representatives worldwide 



Circle 203 on inquiry card. 



September 1979 © BYTE Publications Inc 



69 



A Low-Speed Analog-to-Digital 
Converter for the Apple II 



Richard C Hallgren 

Assistant Professor 

Michigan State University 

College of Osteopathic Medicine, 

Dept of Biomechanics 

East Lansing MI 48824 



The development of micropro- 
cessor-based computer systems has 
progressed to the point where it is 
now practical to utilize these systems 
in a scientific or laboratory applica- 
tion. To be useful in a scientific appli- 
cation the computer must have the 
capability o/ converting analog 
signals to digital signals. Very few 
home computers have this capability. 
Certainly it is a straightforward task 
to design an analog-to-digital con- 
verter (ADC), but the real problem 
lies in connecting the converter to the 
computer. 

The Apple II computer, with 8 
peripheral-board connectors on the 
mother board, makes the job of 
designing and implementing special 
interfaces (such as the ADC) rela- 
tively easy. The peripheral-board 
connectors give the hardware 
designer access to all address, data, 
and control lines. In addition all con- 
trol, address, and data lines have 
been buffered, and certain address 
bits have been decoded to give a 
device select (DS) signal. What 
this means is that when a specific 
range of address locations is accessed, 
the DS line will give a low output 
signal. Since the peripheral-board 
connectors are on the main computer 



About the Author 

Richard Hallgren is an Assistant Professor in 
the Dept of Biomechanics at Michigan State 
University. He is working on the application of 
microprocessor-based systems in scientific 
research. 



IC1 


MC 14028 


16 


a 


IC2 


MC14049 


1 


B 


IC3 


SN7427 


14 


7 


IC4 


MC14013 


14 


7 


IC5 


MC14433 


24 


13 


IC6 


AD580 


— 


— 


IC7 


MC14503 


16 


8 


IC8 


MC14503 


16 


a 


IC9 


DM7432 


14 


7 



Number Type +5V GND -5V 



12 



Table 1: Voltages which must be supplied 
to integrated circuits in figure 1 for 
operating power. 



board, the finished interface board 
will be inside the computer and will 
be able to use the computer's power 
supply. Because of these character- 
istics, turning the Apple II into a real- 
time data analyzer becomes a matter 
of designing an analog-to-digital con- 
verter circuit, and control logic to 
meet the need of the application. 

Many of the applications that I had 
in mind were to be of a low-speed 
nature (eg: monitoring the tempera- 
ture of experimental animals in 
medical physiology laboratories, 
analyzing the results of elec- 
trophoretic analysis). Therefore, a 
low-speed analog-to-digital converter 
built around the Motorola MC14433 
integrated circuit seemed to be a cost 
effective approach. I was inspired by 
Steve Ciarcia's article, "On a Test 
Equipment Diet? Try an 8 Channel 
DVM Cocktail!" (December 1977 
BYTE, page 76). 

The left section of figure 1 shows 
the analog-to-digital converter cir- 



cuitry. All data and status lines to the 
computer are isolated through the 
MC14503 3-state buffers (IC7 and 
IC8). The MC14433 (IC5) is allowed 
to convert continuously at a rate of 
approximately 15 conversions per 
second. This means that if the data 
transfer to memory starts immedi- 
ately after the conversion ends, the 
Apple II can easily decode and store 
the data from one conversion before 
another conversion occurs. IC4, con- 
figured as an RS flip-flop that is in- 
itially reset by the computer, is set by 
the MC14433 after an analog-to- 
digital conversion has been com- 
pleted. When the computer senses 
this change in status, it starts the 
decoding and data transfer process. 
IC6 is an AD 580 used to provide a 
stable reference voltage to the 
MC14433. 

The right section of figure 1 shows 
the control logic that is necessary to 
coordinate the transfer of data to the 
computer, and control signals from 
the computer. The circuit is designed 
so that the peripheral card resides in 
I/O (input/output) slot 7 on the 
Apple II mother board. The device 
select signal will go low whenever 
hexadecimal memory locations C0F0 
thru COFF are addressed. The least 

Text continued on page 74 

Figure 1: Schematic diagram of analog-to- 
digital-conversion circuit and associated 
control-logic circuitry. The analog-to- 
digital (A/D) converter is shown on the 
left side, the control logic on the right 
side . »_ 



70 September 1979 © BYTE Publications Inc 



ANALOG-TO-DIGITAL CONVERSION CIRCUIT 



^ — | 0-1.999 
■^ 1 VOLTS 




D7 D6 



D5 04 D3 D2 Dl DO 



R/W DS 



September 1979 © BYTE Publications lnc 71 



Circle 379 on inquiry card. 



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( CALL FROM "\ 
V ^ BASIC ROUTINE^ / 



SAVE A,X, AND 
Y REGISTERS 



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DATA STORAGE 
LOCATION 



YES 



(RETURN TO ^ 
BASIC ROUTINE J 




INPUT DIGIT 
CODE AND DIGIT 




YES 



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YES 




Figure 2: Flowchart of the machine language subroutine which takes samples from the 
analog-to-digital converter. This code is written for the 6502 processor used in the 
Apple II. 



72 



September 1979 © BYTE Publications Inc 



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Circle 46 on inquiry card. 



BYTE September 1979 73 



Address Instruction Op Code Operand Comments 



4000 

4003 

4006 

4009 

400A 

400C 

400E 

4010 

4012 

4014 

4016 

4019 

401 B 

401 E 

401 F 

4022 

4024 

4026 

4029 

402C 

402F 

4030 

4031 

4032 

4033 

4036 

4D37 

4038 

4039 

403A 

403B 

403C 

403D 

403E 

403 F 

4040 

4043 

4046 

4048 

404A 

404C 

404F 

4052 

4054 

4056 

4058 

405B 

405 D 

405F 

4061 

4062 

4064 

4066 

4068 

4069 

406B 

406E 

4071 

4073 

4075 

4077 

407A 

407C 

407E 

4080 

4081 

4083 

4085 

4087 

4088 

408A 

408D 

4090 

4092 

4094 

4096 

4099 

409B 

409D 

409 F 

40A0 



AD B0 
8E B1 
8C B2 
08 

A2 00 
A9 00 
85 0A 
A9 4A 
85 0B 
A9 00 
8D A0 
A9 4E 
8D A1 
78 

AD A1 
C5 OB 
DO OB 
AD BO 
AE B1 
AC B2 
28 
60 
58 
EA 

4C 1E 
EA 
EA 
EA 
EA 
EA 
EA 
EA 
EA 
EA 
EA 

8D F2 
AD F1 
29 80 
C9 80 
DO F7 
AD FO 
8D A2 
29 80 
C9 80 
DO F4 
AD A2 
29 OF 
81 OA 

A4 OA 
C8 

84 OA 

DO 05 

A4 OB 
C8 

84 OB 

AD FO 

8D A2 

29 40 

C9 40 

DO F4 

AD A2 

29 OF 

81 OA 

A4 OA 
C8 

84 OA 

DO 05 

A4 OB 
C8 

84 OB 

AD FO 

8D A2 

29 20 

C9 20 

DO F4 

AD A2 

29 OF 

81 OA 

A4 OA 
C8 

84 OA 



49 LDA 
49 STX 
49 STY 
PHP 
LDX 
LDA 
STA 
LDA 
STA 
LDA 
49 STA 
LDA 
49 STA 
SEI 
49 LDA 
CMP 
BNE 
49 LDA 
49 LDX 
49 LDY 
PLP 
RTS 
CLI 
NOP 
40 JMP 
NOP 
NOP 
NOP 
NOP 
NOP 
NOP 
NOP 
NOP 
NOP 
NOP 
CO STA 
CO LDA 
AND 
CMP 
BNE 
CO LDA 
49 STA 
AND 
CMP 
BNE 
49 LDA 
AND 
STA 

LDY 
INY 
STY 
BNE 
LDY 
INY 
STY 
CO LDA 
49 STA 
AND 
CMP 
BNE 
49 LDA 
AND 
STA 
LDY 
INY 
STY 
BNE 
LDY 
INY 
STY 
CO LDA 
49 STA 
AND 
CMP 
BNE 
49 LDA 
AND 
STA 
LDY 
INY 
STY 



$49 BO 

$49B1 Save registers 

$49B2 

#$00 

#$00 

$0A Starting location of data storage 

#$4A 

$0B 

#$00 

$49A0 Final location of data storage 

#$4E 

$49A1 

Disable interrupt 
$49A1 
$0B 

$4031 Have all data locations been filled? 
$49B0 
$49B1 
$49B2 



$401 E 



$C0F2 

$C0F1 

#$80 

#$80 

$4043 

$C0F0 

$49A2 

#$80 



$0A 

$0A 

$406B 

$0B 

$0B 

$C0F0 

$49A2 

#$40 

#$40 

$406B 

$49A2 

#$0F 

($0A,X) 

$0A 

$0A 

$408A 

$0B 

$0B 

$C0F0 

$49A2 

#$20 

#$20 

$408A 

$49A2 

#$0F 

($0A,X) 

$0A 

$0A 



Enable Interrupt 



Start A/D conversion 



A/D conversion finished? 

Input data 

Temporary data storage 



#$80 Check for first digit (MSD) 

$404C 

$49A2 

#$0F 

($0A,X) 



Peel off digit code leaving data 
Store data 



Increment lower 8 bits of data storage 
Carry out to upper 8 bits? 
Increment upper 8 bits of data storage 
Input data 

Check for second digit 

Peel off digit code leaving data 
Store data 

Increment lower 8 bits of data storage 

Carry out to upper 8 bits? 

Increment upper 8 bits of data storage 

Input data 

Check for third digit 



Peel off digit code leaving data 
Store data 

Increment lower 8 bits of data storage 



Listing 1: The machine language 
subroutine for collecting data from the 
analog-to-digital converter, here shown in 
assembly language format. Memory loca- 
tions 03FE and 03FF contain the hex- 
adecimal interrupt jump vector 4040, 
which is the entry point of this routine. 



Text continued from page 70: 

significant 4 bits of the address are 
decoded by ICl and are used for on 
board addressing. Performing a store 
accumulator (STA) operation to loca- 
tion C0F2 causes the SC (start conver- 
sion) line to go high and resets the 
flip-flop IC4. Performing a LDA 
(load accumulator) from hexadecimal 
location C0F1 transfers the end of 
conversion (EOC) and overrange 
(OR) status data into the computer. 
Performing a LDA from location 
C0F0 transfers the digit-select code 
and the binary coded decimal (BCD) 
value of the particular digit selected 
into the computer. 

The software portion of the analog- 
to-digital converter project is divided 
into 2 parts: 

• A machine language routine to 
provide high-speed transfer of 
data from the MC14433 to the 
computer memory. 

• A BASIC routine written in 
Applesoft floating-point BASIC to 
take the data in memory and for- 
mat it into a voltage that can be 
displayed as a function of time 
with the high-resolution graphics 
routine. 

Since the Apple II does not have an 
internal real-time clock, I decided to 
use the interrupt request line (IRQ) 
as an input for an external clock. The 
advantage to this is that a calibrated 
pulse generator can be used to deter- 
mine the sampling rate. If desired, the 
computer can perform other tasks 
between samples. Knowing when 
each sample was taken makes it possi- 
ble to display the data as a function of 
time with the high-resolution 
graphics routine. Since the Apple II 
high-resolution graphics allows the 
display of 256 points I decided to 
store 256 points in memory before 
displaying the data, but there is no 
reason why the data could not be 
displayed as it is taken. Figure 2 
shows the flowchart of the machine 
language program, and listing 1 



74 September 1979 © BYTE Publications Inc 



6809! 

S-100 Compatibility.6809 Computability. 




6809 

16 bit internal arithmetic 
Hardware multiplication 
Two stack pointers 
Two index registers 
18 addressing modes 
Fully relocatable code 
Five interrupts 
Up to three times the 
throughput of a 4MHz Z-80 



• 1K RAM 

• 10K PROM space 

• MONBUG II monitor included 

• 2400 baud cassette interface 

• 20 I/O lines 

• RS-232 level shifters 

• Real time clock 

• DMA 

• Parallel keyboard input 

• Memory-mapped video output 

• Fully S-100 compatible 

(including 8080 type I/O) 

• A complete system, ready to use. 



MD-690a Single Board Computer 
$239 kit $299 assembled 

6802 Processor also available 
Ask about 6802, 6809 and Z80 systems. 



Please rush the following: 

D CPU Card (kit) 

□ CPU Card (assembled) 



Name 

Address 
Company 

City 

State/Zip 



MicroDaSys 

P.O. Box 36051 

Los Angeles, CA 90036 

(213)935-4555 



CA residents add 6%. 
Visa and Mastercharge accepted. 



Circle 221 on inquiry card. 



BYTE September 1979 



75 



Carry out to upper 8 bits? 

Increment upper 8 bits of data storage 

Input data 

Check for LSD (least significant digit) 

Peel off digit code leaving data 
Store data 

Increment lower 8 bits of data storage 

Carry out to upper 8 bits? 

Increment upper 8 bits of data storage 

Return from interrupt 



Listing 2: Program in Applesoft floating point BASIC which calls the machine language 
routine of listing 1 and then formats and displays the data received, using the high- 
resolution graphics capability of the Apple II. 



40A2 


DO 


05 


BNE 


$40A9 


40A4 


A4 


OB 


LDY 


SOB 


40A6 


C8 




INY 




40A7 


84 


OB 


STY 


SOB 


40A9 


AD 


F0 


CO LDA 


SCOFO 


40AC 


8D 


A2 


49 STA 


S49A2 


40AF 


29 


10 


AND 


#$10 


40B1 


C9 


10 


CMP 


#$10 


40B3 


DO 


F4 


BNE 


$40A9 


40B5 


AD 


A2 


49 LDA 


S49A2 


40B8 


29 


OF 


AND 


#$0F 


40BA 


81 


0A 


STA 


($0A,X) 


40BC 


A4 


0A 


LDY 


$0A 


40BE 


C8 




INY 




40BF 


84 


0A 


STY 


$0A 


40C1 


DO 


05 


BNE 


$40C8 


40C3 


A4 


0B 


LDY 


$0B 


40C5 


C8 




INY 




40C6 


84 


OB 


STY 


SOB 


40C8 


A5 


45 


LDA 


$45 


40CA 


40 




RTI 





Program 

100 DIM Z (300) 

101 HOME 

102 GOTO 1000 

110 CALL 16384 

1 1 1 HOME : VTAB 24 

112 PRINT "THE DIGITIZED DATA IS 

BEING FORMATTED FOR PLOT 
ING" 

113 X= 18944 

115 FORJ = 0TO255 

120 V1 = PEEK(X) 

122 V2=PEEK(X + 1) 

124 V3=PEEK(X + 2) 

126 V4 = PEEK(X + 3) 

128 X = X + 4 

130 IF V1 > 7 THEN V1 = 

132 IF V1 = OTHEN GOTO 140 

134 V1 = 1 

140 V$ = STR$ (V1) + STR$ (V2) + 

STR$ (V3) + STR$ (V4) 

150 Z(J) = VAL(V$)/1000 

160 NEXT J 

200 HGR: HCOLOR = 3 

202 HPLOT 20,0 TO 20,150 

204 HPLOT TO 279,150 

208 HPLOT 18,0 TO 22,0 

210 HPLOT 18,10 TO 22,10 

212 HPLOT 18,20 TO 22,20 

214 HPLOT 18,30 TO 22,30 

216 HPLOT 18,40 TO 22,40 

218 HPLOT 18,50 TO 22,50 

220 HPLOT 18,60 TO 22,60 

222 HPLOT 18,70 TO 22,70 

224 HPLOT 18,80 TO 22,80 

226 HPLOT 18,90 TO 22,90 

228 HPLOT 18,100 TO 22,100 

230 HPLOT 18,1 10 TO 22,110 

232 HPLOT 18,120 TO 22,120 

234 HPLOT 18,130 TO 22,130 

236 HPLOT 18,140 TO 22,140 

238 HPLOT 18,150 TO 22,150 

240 HPLOT 4,47 TO 4,53 

242 HPLOT 7,53 

246 HPLOT 10,47 TO 10,53 

248 HPLOT TO 14,53 

250 HPLOT TO 14,47 

252 HPLOT TO 10,47 

260 HPLOT 7,103 

262 HPLOT 14,97 TO 10,97 



Comments 



Machine language routine 



Starting address of data 

Get first digit (MSD) 
Get second digit 
Get third digit 
Get fourth digit (LSD) 



Decode MSD 

Convert digits into voltage XXX. X 

High-resolution graphics 



Plot X-Y axis 



Figure 3: Flowchart of the BASIC pro- 
gram which calls the machine language 
subroutine, formats the data obtained 
from the analog-to-digital converter, and 
displays it using high-resolution graphics. 



( start J 



CALL MACHINE 
LANGUAGE ROUTINE 



INITIALIZE 
DATA STORAGE 
LOCATION 



GET 4 DIGITS 



FORMAT INTO 
VOLTAGE 




PLOT X, Y AXIS 



PLOT VOLTAGE 
SAMPLES 



YES 




f STOP J 



Listing 2 continued on page 78 



shows the coded program with com- 
ments. 

Upon entering the subroutine, all 
of the necessary registers are saved to 
enable a successful return from 
subroutine. The first thing that 
happens is that the end of conversion 
flip-flop is reset and the program 
loops until the MC14433 completes 
the next conversion and sets the flip- 
flop. The program then samples the 
data lines and decides whether or not 
the data represents the most signifi- 
cant piece of data. If it does not, the 
program continues to sample the data 
lines until the most significant piece 
of data has been obtained. This 
datum is then stored in memory, the 
memory storage locations are in- 



76 September 1979 © BYTE Publications Inc 




w^^JutMyf^fH 




(Mud 



announcement I. The first eight Personal 
'rograms 8 from Aladdin Automation are 
waiting for you now at your neighborhood 
omputer retailer or direct from Aladdin. 

low you can get your full share of Aladdin 
lagic in every one of these Personal 
'rograms 8 : 

Math-Tor-Mind A delightful, 
educational learning experience 
for your pre-school child. Watch 
le smile on your child's face as a correct 
nswer makes the mathematician smile on the 
:reen before you. A nursery song also serves 
3 a reward for learning elementary addition 
nd subtraction. With Aladdin's Math-Ter- 
1ind s your child's pathway to learning will be 
jn-filled . . . for both of you. Math-Ter-Mind 8 . 
ne first release from the Aladdin Education® 
eries. (nursery song currently available only 
n Apple II"" program) 

Lunar Lander In a controlled 
descent, you're |ust seconds away 
from your first landing on the cold. 
nbidding surface of the moon. As you 
avigate your delicate spacecraft downward to 
le safety of Moonbase. you must be ever 
/atchful of the dangers rising to meet you with 
ach passing moment: a fuel level fast 
pproaching zero; deadly meteor showers that 
ome from any direction, at any time; sheer- 
jced rock cliffs and rough terrain; choosing 
^e correct landing pattern and rate of descent. 
Jaddin's Lunar Lander. Your chance to reach 
ut and touch the stars . . . without leaving the 
afety and comfort of your own chair. The first 
?lease from the Aladdin Simulation 8 Series. 



Craps All eyes in the casino are 
on you. The dice are in your 
hands. Lady Luck sits at your 
shoulder, whispering . . . "Just one more time. 
Try your luck |ust one more time." You throw 
. . . and watch the dice tumbling on the 
screen. With Aladdin's Craps you play against 
the computer, so it's awfully tough to win. But 
when you do. it's an experience you're likely 
never to forget. Craps. An exciting, heart- 
pounding Personal Program 8 . The first release 
from the Aladdin Las Vegas* Series. 

Mastermind A challenging game 
of intrigue, centuries old, that will 
give you full chance to test your 
powers of logic, deduction and reason. And 
test them you will, as you try and solve the 
computer's puzzle, using clues as they're 
provided one-by-one. You control the degree of 
difficulty in this classic Personal Program 8 that 
offers one simple, yet all-consuming challenge; 
beat the Mastermind in a direct, one-on-one 
battle of wits. Aladdin's Mastermind. The first 
release from the Aladdin Old Favorites 8 Series. 

Tic-Tac-Toe Five different levels 
of difficulty allow a person of any 
age or skill to take part in this 
relaxing, enjoyable game that can act as a 
learning tool, as well. Level I. for example, is 
suitable for children and is excellent also for 
teaching simple mathematics. The computer 
plays just about perfectly at Level V. Just 
about, that is. so go ahead and take your best 
shot. See if you can beat the computer in this 
traditional favorite of young and old alike. 
Tic-Tac-Toe. Another first release from the 
Aladdin Old Favorites"' Series. 



Jungle Island 8 Shipwrecked in a 
raging storm at sea, miraculously 
you survive only to find yourself 
stranded on a seemingly deserted jungle 
island. Without food, water or supplies of any 
kind, you begin to try and find your way to 
safety. The computer will be your eyes and 
ears as you explore your jungle island and all 
the mysteries and dangers that lie in wait for 
you. Jungle Island 8 A captivating first 
release from the Aladdin Adventure 8 Series. 

Stix- Aladdin's Stix'" can be 
played with 2 to 5 piles of st icks 
and between 1 and 1 9 sticks in 
each pile. The object: to be the one to pick up 
the last stick. Sounds simple? Yes. but you're 
playing against the computer. Take heart, 
though, because you can control the degree of 
difficulty in this update of the ancient game of 
Nim. Stix 8 . Another first release from the 
Aladdin Old Favorites 8 Series. 

Super Pro Football 8 Here's your 
chance to be more than just an 
armchair quarterback. With 
Aladdin's Super Pro Football"' you can replay 
any Super Bowl game, from the first, between 
Green Bay and Oakland, to last year's classic 
victory by Pittsburgh over Dallas. For once you 
can turn back the clock and go for that one big 
play that made the difference between victory 
and defeat in pro football's biggest game of all. 
Super Pro Football 8 . The first exciting release 
from the Aladdin Super Pro 8 Series 

Visit your neighborhood computer retailer or 
contact Aladdin direct to get your full share of 
the magic in Announcement I. the first eight 
Personal Programs"" from Aladdin Automation. 




lath-Ter-Mind 8 



Lunar Lander 



Craps 



Mastermind Tic-Tac-Toe Jungle Island" Stix 9 



Super Pro Football* 



Velcome to the All-New World of 
uaddin. And Get Ready to 
flake Your Own Magic 

ircle 3 on inquiry card. 




A/CON AJVJMAWON, NC. 
'AJDON COMPUTB? CORR 

3420 Kenyon Street, Ste. 131, San Diego, CA 92110 



opyright 1978 by Aladdin Automation 



Design and copy by Campbell Marsh Graphic Communications 



Listing 2 continued: 



264 


HPLOT TO 10,100 


266 


HPLOT TO 14,100 


268 


HPLOT TO 14,103 


270 


HPLOT TO 10,103 


272 


HPLOT 14,147 TO 10,147 


274 


HPLOT TO 10,153 


276 


HPLOT TO 14,153 


278 


HPLOT TO 14,147 


280 


HPLOT 30,148 TO 30,152 


281 


HPLOT 40,148 TO 40,152: HPLOT 




50,148 TO 50,152 


282 


HPLOT 60,148 TO 60,152: HPLOT 




70,148 TO 70,152 


283 


HPLOT 80,148 TO 80,152: HPLOT 




90,148 TO 90,152 


284 


HPLOT 100,148 TO 100,152: HPLOT 




110,148 TO 110,152 


285 


HPLOT 120,148 TO 120,152: HPLOT 




130,148 TO 130,152 


286 


HPLOT 140,148 TO 140,152: HPLOT 




150,148 TO 150,152 


287 


HPLOT 160,148 TO 160,152: HPLOT 




170,148 TO 170,152 


288 


HPLOT 180,148 TO 180,152: HPLOT 




190,148 TO 190,152 


289 


HPLOT 200,148 TO 200,152: HPLOT 




210,148 TO 210,152 


290 


HPLOT 220,148 TO 220,152: HPLOT 




230,148 TO 230,152 


291 


HPLOT 240,148 TO 240,152: HPLOT 




250,148 TO 250,152 


292 


HPLOT 260,148 TO 260,152: HPLOT 




270,148 TO 270,152 


300 


FOR J = TO 255 


310 


HPLOT J + 20,150 - (Z(J) * 100) 


320 


NEXT J 


1000 


PRINT "PRESS RETURN TO START A/D 


1010 


K = PEEK( - 16384) 


1012 


POKE - 16368,0 


1014 


IFK > 127 THEN GOTO 1020 


1016 


GOTO 1010 


1020 


TEXT 


1022 


HOME 


1024 


VTAB 24 


1026 


PRINT "256 DATA POINTS ARE 




BEING DIGITIZED" 


1028 


GOTO 110 


1099 


END 



Photo 1: High-resolution display of a 0.05 
Hz sine wave signal which has been 
digitized at 10 samples per second. 



Plot voltage 



cremented, and the program begins to 
look for the 2nd piece of data. After 
the 4 digits representing the digitized 
voltage have been stored, the pro- 
gram checks to see if 256 samples 
have been stored. If they have not, 
control returns to the beginning of the 
subroutine. When all 256 samples 
have been stored, the program 
returns to the BASIC routine which 
called it. 

The BASIC routine has the task of 
assembling the 4 digits from each con- 
version into a single number which is 
equal to the measured voltage. A 
flowchart is shown in figure 3. The 
machine language assembly routine 
has previously taken each of the 4 
digits from a single conversion and 
has stored them in individual 
memory locations. The BASIC 
routine uses the string manipulation 
capabilities of Applesoft BASIC to 
fetch each digit from its memory loca- 
tion and to assemble all 4 digits into a 



single 4-digit voltage. After all 256 
conversions have been changed into 
voltages and stored in a matrix array, 
the high-resolution graphics routine is 
called and the voltages are plotted as 
a function of time. It is convenient to 
have the voltages stored in a matrix 
array so that if further analysis of the 
data is required it can be easily 
retrieved. Listing 2 shows the coded 
BASIC program with comments. 

To demonstrate the ability of a 
system to digitize and display low- 
frequency signals, a waveform 
generator was connected to the 
analog-to-digital converter. Photo 1 
shows a 0.05 Hz sine wave which was 
digitized at 10 samples per second. 
Photo 2 shows a 0.05 Hz triangular 
wave which was digitized at 10 
samples per second. Photo 3 shows a 
0.001 Hz sine wave which was digitiz- 
ed at 1 sample per minute. The results 
are even more impressive when you 
consider that this is a data-acquisition 




Photo 2: Display of a 0.05 Hz triangular 
wave digitized at 10 samples per second. 



..." ..■■■-.■■■-■■■■ ■ ■ 




wmE^ 1 ^^ 





Photo 3: Display of a 0.001 Hz sine wave 
digitized at 1 sample per minute. 




system costing less than $2,000. 

At present, a high-speed analog-to- 
digital converter is being constructed 
to digitize and analyze the electro- 
myographic voltages which come 
from muscles. This will allow an in- 
vestigator to gather data for further 
analysis of the complex neural- 
impulse waveform resulting from 
stretching a muscle. I anticipate that 
once researchers become aware of the 
data acquisition, data analysis, and 
system control that are possible with 
these low-cost systems, there will be a 
drastic increase in their use.H 



78 September 1979 © BYTE Publications Inc 



Circle 99 on inquiry card. 



DIABLO PROVES 
LOOKS ARE EVERYTHING. 

With Diablo's printers and terminals, you can always be sure that beauty will be 
in the eyes of the beholder. Because no one knows more about print wheel technology than 
the company that invented it in the first place. 

Diablo's metal and plastic wheel printers have established industry standards for crisp, 
clear characters, proportional spacing, and uniform density. 

So, when you're ready to choose a printer for your own computer, pick the one that 
produces "picture perfect" originals every time. 

If you really want to look good, remember this. With Diablo, you'll always look 
your best. t - 

Diablo Systems 





)iaMd* is a roastered trademark of XEROX CORPORATION. 



^Jp Your 
Output. 



TEMPOS 



MULTI-TASKING! 

The TEMPOS Operating System is quickly becoming the standard in Multi- 
User, Multi-Tasking operating systems for 8080 and Z80 microcomputers. 
Multi-Tasking means that, even with only one user at one terminal, more 
than one job can be running on the system simultaneously! If you have ever 
had to go get a cup of coffee while you wait for your computer to print list- 
ings, you know the advantages of a system that will handle one job while 
you are working on another. TEMPOS is a true time sharing system, and 
the maximum number ol jobs is limited only by your memory. 

MULTI-USER! 

Want to share your computer with another user? With TEMPOS all it takes 
is another terminal ... up to seven interactive terminals are allowed! And 
with Re-Entrant programs, each user does not need a complete copy in 
memory. We include three Re-Entrant programs (the OPUS/THREE High- 
Level Language, the TEXTED Text Editor, and FILES, a disc file 
directory/manipulator) or write your own! In addition, we include an 
assembler, a linking loader, over a half-dozen other utility programs and 
over 60 system subroutines, callable by the programmer! 

PROVEN! 

With TEMPOS, you get a package that has been tested in our facilities for 
over two years, and in the field at over 50 different installations. We have 
used this system ourselves for everything from writing high-level languages 
to developing applications to text editing to games. TEMPOS is undoubted- 
ly the most flexible software tool on the market . . . and you can have it for 
much less than you think! 

COMPATIBLE! 

TEMPOS is available for many different systems; prewritten drivers may 
include yours. Or, using our interactive System Generation Routine, you 
can add your own. Call or write now for our free catalog and the name of a 
dealer near you. The TEMPOS Operating System is available for $787.00, 
the manual set ( price may be credited toward the purchase of the TEMPOS 
package) for $21.50 (prices include shipping within the U.S.). 

ADMINISTRATIVE 
□□SYSTEMS 
□□□INC. 
□□ 

1642 S. Parker Road, Suite 300, Denver, Colorado 80231 
(303) 755-9694 



BYTEs Bits 



EXPAND YOUR 

COMPUTER'S 

POTENTIAL WITH 

NEW TIMESHARING 

SERVICE 

CompuServe, a Columbus 
Ohio computer service 
organization which services 
more than 650 commercial 
customers including govern- 
ment agencies, financial 
institutions, and large cor- 
porations, has recently ex- 
panded its services to en- 
compass the personal com- 
puter user. MicroNET is a 
computer timesharing and 
software distribution service 
for home and small business 
applications. The service 
costs $5 per connect hour. 
The MicroNET system may 
be accessed via telephone 
service in 25 major metro- 
politan areas. It is available 
between the hours of 6 PM 
and 5 AM on weekdays, as 
well as all day Saturday, 
Sunday and holidays. 

According to the com- 
pany, the personal computer 
owner will be able to use a 
variety of computer pro- 
grams on a timesharing 
basis; communicate with 
other MicroNET customers; 
buy and sell software 
through the network; and 
obtain additional on-line 
storage. The MicroNET 
timesharing library includes 
a large selection of programs 
in several categories inclu- 
ding personal programs, 
educational aids, business 
applications, games and 
simulations, programming 
languages, and programming 
and diagnostic tools. Most 
of the programs in the 
MicroNET library are 
available at no charge other 
than the basic connect time 
rate. 

All connect time charges 
and software purchases will 
be billed through use of 
credit card information 
which is provided by the 



customer. For a Service 
Application form and more 
information, write to Per- 
sonal Computing Division, 
CompuServe Inc, 5000 Ar- 
lington Centre Blvd, Colum- 
bus OH 43220, or call (614) 
457-8600. 



NOTES ON 
BULLETIN BOARD 

The Computerized 
Bulletin Board System 
(CBBS) in the Atlanta GA 
area is no longer being 
operated by DC Hayes 
Associates Inc. The Atlanta 
system is now being 
operated by the Atlanta 
Computer Society. The 
telephone number has been 
changed to (404) 394-4220. 
A description of a CBBS ap- 
peared in the article entitled 
"Hobbyist Computerized 
Bulletin Board" by Ward 
Christensen and Randy 
Suess, (November 1978 
BYTE, page 150). 



CITRUS COLLEGE 

OFFERS PERSONAL 

COMPUTING COURSES 

Citrus College in Azusa 
CA is offering 2 personal 
computing courses to com- 
mence September 1979. Each 
class is 18 weeks long. The 
classes are: 

Personal Computing 
-Building and Using (DP 
115) Basic construction 
techniques, reading sim- 
ple logic diagrams, 
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80 



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BYTE September 1979 81 



Technical Fonum 



Operating Systems 
Let's Have Some UNIX-Inspired Software 



Jim Howell, 5472 Playa Del Rey, San Jose CA 95123 

I would like to add to the comments made by James 
Jones ("Languages Forum," April 1979 BYTE, page 245) 
about operating systems. 

First, I wholeheartedly agree with his letter. A job con- 
trol language like OS/370 (or most other large systems, 
for that matter) would be terrible for personal computer 
use. Aside from the pile of job control required to do 
anything, there are other problems with OS-like systems. 
The numerous file formats and "access methods" make it 
difficult for programs to work together. Specifying files 
for the compiler or assembler to use as work files is a 
nuisance. A file specification (DD statement) also re- 
quires giving values for several parameters about which 
the user usually doesn't care or shouldn't have to specify. 
Some of these problems are helped by using procedures 
(sets of job control that the computer vendor or local 
systems programmer has stored on disk for general use), 
but these may not be what you need, and they also take 
up disk space. The space is not significant if your disks 
store 100 megabytes, but it could be significant for flop- 
py disk users. 

I would like to strengthen Mr Jones' suggestions that 
UNIX be used as a model for a microprocessor operating 
system. (UNIX is a trademark of Bell Labs.) I have used a 
UNIX system at work for about a year and it is a very 
pleasant system to work with. All files on UNIX are a 
series of bytes: no structure within files are imposed by 
the system. In particular, there is no concept of a "logical 
record" in UNIX. A "logical record" is the (usually) fixed 
size chunk in which files are read or written on big 
systems; often 80 bytes (for card or card-image files), or 
120 or 132 bytes (for line printers). On UNIX, the end of a 
line in a text file is indicated by the use of a new-line 
character. This new-line character (line feed on UNIX) 
replaces the trailing blanks which are stored on systems 
that use logical records. The new-line character is read or 
written just like any other character. The size of a file is 
determined by how many bytes are written to it; pre- 
determination of the file size (by guessing?) is not 
necessary, or even possible. 

Job control language on UNIX is practically non- 
existent. A command to run a program (such as a com- 
piler or a user program) consists of the name of the pro- 



gram to be executed followed by any parameters that the 
program needs, separated by blanks. (Parameters are 
often file names and processing options.) The command 
processor, which runs as a user program, reads the com- 
mand line, divides it into "words," and calls the system to 
execute the desired program. This system call also passes 
the parameters to the executed program. There is no need 
to describe files in the command since programs need on- 
ly the name of a file in order to access it. Block sizes and 
such things are not required, even for new files, since 
there is only one format for files. 

The following is a summary of the major system calls 
of UNIX that deal with file or an I/O (input/output) 
device. A file name in the open and create calls can also 
be a device name (such as the name for a terminal or 
printer). 

Open (name, mode) opens an existing file (or device) 
for further operations. "Name" is a pointer to a 
character string which is the name of the file (or 
device) and "mode" indicates reading, writing, or 
both. 

Create (name, prot) creates a new file, deleting any old 
file whose name is "name." This new file is open- 
ed for writing. (I would like to see a "mode" 
argument for this call, in addition to the two 
specified. This "mode" would mean the same as 
it does for "open.") 

Read (fildes, buffer, length) reads up to "length" bytes 
from the file whose descriptor is "fildes" into the 
"buffer". The file descriptor is a small, non- 
negative integer which was returned by open or 
create. The number of bytes actually read is 
returned to the caller. A return of means end of 
file. 

Write (fildes, buffer, length) writes "length bytes to the 
file "fildes" from the "buffer." 

Seek (fildes, offset, base) moves the read/write 
pointer of the file "fildes" to a new position 
within the file. "Offset" is how far to move the 
pointer, and "base" indicates from the start of the 
file, from the current position, or from the end of 
the file. 

Close (fildes) closes a file. 

Each open file has a read/write pointer associated with 



82 September 1979 © BYTE Publications Inc 



it. Each read or write call starts reading or writing at the 
current pointer and advances the pointer by the number 
of bytes read or written. By moving the read/write 
pointer with the "seek" call, random access files (or even 
indexed-sequential or other access methods) can be 
implemented if required. Note that "read" and "write" are 
the lowest levels of I/O calls to the system, and that they 
apply to all devices. All device-dependent processing is 
inside of the operating system. The only thing that a user 
program needs to know about a file after it is opened or 
created is the returned number (file descriptor). There are 
no "control blocks" or other system-imposed structures 
in user programs. (System calls are available in UNIX to 
determine the type of device that is associated with an 
open file for the few programs that need this 
information.) 

Most current microprocessor operating systems use a 
special character, such as control-z, to mark the end of 
text files. These systems take the view that "binary" files 
(files where all 256 possible bytes are valid) are only for 
executable programs, and in this case reading a few extra 
bytes from the last sector of the file will not cause any 
problems. Such a scheme prevents the use of binary files 
for other purposes where the exact end of the file must be 
known. Possible uses include a work file written by a 
compiler or assembler and libraries of subroutines in ob- 
ject format for linking with other programs. (For example 
you wouldn't want a 20 byte absolute value function to 
add 128 bytes to your program, simply because the end 
of a sector is the best you can do at locating the end of the 
function!) The end of a file should, as in UNIX, be indi- 
cated by a count of the number of bytes in the file, and 
the end of file when reading should be determined by 
comparing the read/write pointer of the file to the end-of- 
file byte count. (Writing past the end of a file causes the 
end of file pointer to move to the new read/write pointer 
position.) 

The above is a description of some aspects of UNIX, 
and is also intended to be used as guidelines in writing 
any new operating systems for microprocessors (or even 
big systems). One other thing that might be considered 
by an operating system writer is the use of a high-level 
language for most of the operating system and for the 
programs that implement supplied commands. This 
would allow the operating system to be moved to another 
microprocessor without having to completely rewrite it. 

I am about halfway through designing an operating 
system along the lines of the above suggestions. (I started 
before Mr Jones' letter appeared in BYTE.) Eventually I 
expect to implement it. 

Let me conclude by listing three references which are 
recommended to those who are implementing a usable 
microprocessor operating system. The first two were also 
mentioned by Mr Jones. ■ 



REFERENCES 

1. Communications of the ACM, July 1974. A revised version of the 
UNIX article appears in reference 3 below. 

2. Software Tools by Kernighan and Plauger. 

3. The Bell System Technical Journal, July thru August 1978, part 2. 
This issue contains about fifteen papers on UNIX. Read especially 
the first 3 or 4 papers, as well as the one called "UNIX on a 
Microprocessor" (single-user version on an LIS-11). 




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Soldering Techniques 



William Trimmer 

40 James St 

Morris Plains NJ 07950 



Anyone who can get 3 objects into 
the same vicinity can solder. Doing a 
professional job, however, requires 
some care and practice. This article 
draws on my experience in teaching 



electronics and a fine pamphlet 
prepared by NASA entitled "Solder- 
ing Electrical Connections, A Hand- 
book" (United States Printing Office, 
NASA SP-5002). Good soldering 




Photo 1: After cleaning the tip of the soldering iron with a wet sponge, prepare it by 
adding a dab of solder. 




Photo 2: Before soldering, the joints should be mechanically fastened. 



techniques can save time, com- 
ponents and frustration. 

Good Soldering Techniques 

Good soldering starts with a clean 
soldering iron tip and well-tinned 
parts. Just prior to use, the hot solder- 
ing iron should be cleaned by wiping 
it across a wet sponge. The thermal 
shock and wiping action will clean 
the tip and remove the excess solder. 
Then touch a bit of solder to the tip 
(photo 1). The iron is now ready for 
use. The parts to be soldered are 
ready when the solder flows quickly 
and evenly over their heated surfaces. 
If this does not happen, clean the 
parts by brushing, filing, or rubbing 
with a pencil eraser. Next flow a thin 
layer of solder over the clean surface. 
The parts are now tinned and ready 
to be soldered. 

The prepared parts should be 
mechanically fastened together before 
making the soldering joint (photo 2). 
The solder should not be expected to 
supply mechanical strength. Clean 
the soldering iron tip, and add a dab 
of solder to the tip. Touch the 
soldering iron to the heavier of the 
parts to be joined, and begin wiping 
the solder on the junction between the 
two parts (photo 3). 

Do not feed the solder into the 
soldering iron tip. When the com- 
ponents are hot enough, the solder 
will begin to melt into the joint. The 
solder should skate over the surfaces 
like butter on a hot pan. Now you 
must move quickly. Rapidly wipe the 
entire length of the connection with 
the solder, being careful not to apply 
too much. The solder should flow 
smoothly over the parts. If braided 
wire is used, the strands should still 
be visible (photo 4). Doing this well 
takes a lot of practice. Now remove 



84 September 1979 © BYTE Publications Inc 




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Photo 3: When soldering, touch the iron to the heaviest part. When the joint is hot 
enough, the solder will melt on the side opposite the iron. 



the iron and hold everything perfectly 
still. Any motion while the solder is 
going from the liquid to the solid state 
will cause a cold joint. After the joint 
is cooled, the surface of the solder 
should look like a mirror. A good 
solder joint is an accomplishment. 

A good way to begin might be to 
deliberately make some bad soldering 
joints. First, shake the two wires 
while the solder is cooling. Notice the 
undesirable frosted look. Now try 
leaving the iron on the joint for more 
than several seconds, and you will 
notice that a scum forms. Try putting 
too much solder on the joint. Often 
when this blob cools, the frosted sur- 
face will appear (photo 5). Try to find 
the two oldest wires you can. Twist 
them together and solder them. If 
they are covered with an oxide layer, 
the solder will not transfer from the 
soldering iron tip to the wires. 
Repeated heatings will probably 
cause the solder to melt around the 
joint. Notice how the solder does not 
flow onto the wires, but sticks to 
itself. The joint is now probably hot 
enough to burn the flux. 

Inevitably, one has to unsolder 
some beautifully soldered joints. If 
the joint is that of a straight wire 
through a hole, a pull will often ac- 
complish the task. (Be careful of the 
flying molten solder.) Often, one 
must remove the solder and then un- 
wrap the wire. The best method uses 
a fine mesh of properly fluxed copper 
wire. (An example of this would be 
Solder-Wick, made by Solder 




Photo 4: In a well-soldered braided wire, 
the strands should still be visible. 




Photo 5: Excess solder, poor wetting of 
the wire, frosted surfaces, and blobs of 
solder represent poorly soldered joints. 



Removal Co, 1077 E Edna Place, 
Covina CA 91724. Their 40-4-5 is a 
medium size, 40-6-2 Vi is for large 
joints, and 40-2-5 is for very small 
joints.) Push the mesh against the 
joint with the soldering iron. The 
solder will be wicked from the joint 
into the mesh. Solder suckers are also 
a popular way to remove solder. The 
tool is cocked, placed on a heated 
joint, and released. A plunger pulling 
air through the nozzle of the sucker 
gets most of the solder. This last sug- 
gestion is the least expensive way. 
Hold the circuit board and heat the 
joint. Rap the edge of the board 
smartly on the work bench. Solder 
flies in every direction, but the joint is 
clean. 

Good soldering takes patience and 
practice. Fortunately, if properly 
done, the soldering joints are almost 
never the culprits when a circuit does 
not work. The following are some 
suggestions that will make soldering 
easier. 

Tools 

The soldering iron should be well 
tinned (covered with solder), and 
should quickly raise the joint to the 
working temperature. I prefer a 30 or 
40 W element for a pencil soldering 
iron. Cleaning the tip with a wet 
sponge before soldering will bring the 
tip down to the correct temperature 
range (about 700 °F). This slightly 
greater wattage will allow larger 
pieces to be soldered. Better yet are 
the temperature controlled pencil 
soldering irons. Soldering guns are 
too large and hot for all but the most 
massive soldering joints. If you buy a 
new soldering iron, wrap the tip with 
solder before turning it on. This will 
coat the tip with solder before it gets 
hot enough to oxidize. Place the iron 
in a protective cage towards the back 
of your work bench so that it can not 
burn anything. If the iron is not going 
to be used for a while, unplug it. 

It is very tempting to buy less ex- 
pensive solder. Don't do it. Solder 
costs very little compared to other 
components. The best solder is Eutec- 
tic, which is 63% tin and 37% lead. 
This mixture passes directly from a 
liquid to a solid stage without going 
through a plastic region. As a result, 
good soldering joints are easier to 
make. Solder composition is gener- 
ally given by two numbers, such as 
40-60. The first number is the amount 
of tin, the second is the amount of 



86 



September 1979 © BYTE Publications Inc 



lead. The above solder is less expen- 
sive to make than Eutectic solder 
because tin is the expensive element. 
However, this solder has a plastic 
region of about 180 °F. The joint must 
be held completely motionless while 
the solder is cooling through this 
plastic stage. Always use a rosin flux 
when soldering. Never let your iron 
touch acid flux. An 18 or 20 gauge 
solder with a rosin core works nicely. 
There are a number of other useful 
tools. These include long nose pliers, 
diagonal cutting pliers, wire strip- 
pers, a slotted screwdriver, a dental 
pick, and plastic electrical tape. 

Assembly Before Soldering 

A convenient substrate upon which 
to build electronics is predrilled 
epoxy board. The holes should be on 
0.1 inch centers in a square grid for 
digital work. Typical hole sizes are 
0.042 or 0.062 inches. Vector-type 
terminals (Vector Electronic Co Inc, 
12460 Gladstone Ave, Sylmar CA 
91342) can be pushed into the holes 
and the discrete components soldered 
to the terminals. The majority of 
digital electronics come in the dual- 
in-line packages. A convenient way 
to mount dual-in-line packages is 
with circuit-stick-type subelements 
(Circuit-Stik Inc, 24015 Gardnier St, 
POB 3396, Torrance CA 90510). 
These are very thin sheets of glass 
epoxy with preetched copper lands on 
one side and glue on the other. The 
holes on the subelements are aligned 
with the holes on the predrilled circuit 
board, and carefully pressed 
together. The dual-in-line packages 
and components can then be pushed 
through from the other side of the 
board, and soldered to the preetched 
copper lands. One can then wire the 
correct lands together. Because the 
spacing between the pins of the dual- 
in-line packages is only 0.1 inches, 
hand soldering requires care. When 
working with dual-in-line packages, I 
prefer to solder sockets onto the 
board, and plug the dual-in-line 
packages into the sockets. This 
method makes troubleshooting 
easier. 

It is important to be neat when 
soldering. Try to lay the board out 
logically. Do not crowd the com- 
ponents together. If it is your own 
design, you will probably want to 
add something after the board is 
made. Place all of the resistors the 
same way so that their color codes 



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put indicator on SOD (serial output) line. . .printer interface 
(less drivers). . .total of four 8-bit plus one 6-bit I/O ports • 
Crystal Frequency: 6.144 MHz • Control Switches: reset and 
user (RST 7.5) interrupt . . . additional provisions for RST 5.5, 
6.5 and TRAP interrupts onboard • Counter/Timer: program- 
mable, 14-bit binary • System RAM: 256 bytes located at F800, 
ideal for smaller systems and for use as an isolated stack area in 
expanded systems. . .RAM expandable to 64k via S-100 bus or 
4K on motherboard. 

Monitor ROM (ASCII Keyboard Version): 2k bytes of 
deluxe system monitor ROM located at F000 leaving 0000 free 
for user RAM/ROM. Features include tape load with labeling 
(so that Explorer/85 can locate your specific program auto- 
matically). . .tape dump with labeling. . .examine/change 
contents of memory. . .insert data (such as from a paper tape 
reader). . .warm start (a feature which is especially helpful in 
debugging routines as it allows you to save the contents of the 
registers which might otherwise be lost along with the rest of 
your program when a bug causes it to self-destruct. The warm 
start feature helps you pinpoint the exact line in your program 
that contains an error). . .examine and change all 
registers. . . single step with register display at each break point, 
a debugging/training feature ..go to execution address... 
move blocks of memory from one location to another. . .fill 
blocks of memory with a constant . . . display blocks of memory 
. . .automatic baud rate selection . . . variable display line length 
control (1-255 characters/line). . .channelized I/O monitor 
routine with 8-bit parallel output for high spe ed p rinter . . . 

^NeTronTcsR ftDLtaT, Bep™ Y? ^ - 

| 333 Litchfield Road, New Milford, CT 06676 

I Please send the items checked below — 
D Explorer/85 Level "A" Kit (ASCII 
I Version), $129.95 plus $3 p&h. 
□ Explorer/85 Level "A" Kit (Hex 
I Version), $129.95 plus $3 p&h. 
□ 8k Microsoft BASIC on cassette 
I tape, $64.95 postpaid. 
D 8k Microsoft BASIC in ROM Kit 
I (requires Levels "B," "D," and "E"), 
$99.95 plus $2 p&h. 

□ Level "B" (S-100) Kit, $49.95 plus 
$2 p&h. 

D Level "C" (S-100 6-eard expander) 
Kit, $39.95 plus $2 p&h. 

□ Level "D" (4k RAM) Kit, $69.95 
plus $2 p&h. 

□ Level "E" (EPROM/ROM) Kit, 
$5.95 plus 50C p&h. 

D Deluxe Steel Cabinet for Explorer/ 
85, $49.95 plus $3 p&h. 

□ ASCII Keyboard/Computer Ter- 
minal Kit (features a full 128 character 
set, upper & lower case, full cursor con- 
trol, 75 ohm video output convertible 
to baudot output, selectable baud rate, 
RS232-C or 20 ma. I/O, 32 or 64 char- 
acter by 16 line formats, and can be 
used with either a CRT monitor or a TV 
set (if you have an RF modulator), 
$149.95 plus $2.50 p&h. 



By Netronics 




serial console in and console out channel so that monitor can 
communicate with I/O ports. 

Monitor ROM (Hex Version): Tape load with labeling. . . 
tape dump with labeling. . .examine/change contents of mem- 
ory... insert data... warm start. . .examine and change all 
registers. . .single step with register display at each break point 
. . .go to execution address. 

Level "B" Specifications 

Level"B" provides the S-100 signals plus buffers/drivers to 
support up to six S-100 bus boards and includes: address 
decoding for onboard 4k RAM expansion selectable in 4k 
blocks. . .address decoding for onboard 8k EPROM expansion 
selectable in 8k blocks. . .address and data bus drivers for 
onboard expansion . . . wait state generator (jumper selectable), 
to allow the use of slower memories. . .two separate 5 volt 
regulators to insure maximum stability and a noise free bus. 
Level "C" Specifications 

Level "C" expands Explorer's motherboard with a card cage, 
allowing you to plug up to six S-100 cards directly into the 
motherboard. Both cage and cards are neatly contained inside 
Explorer's deluxe steel cabinet. Level "C" includes a sheet 
metal superstructure, a 5-card gold plated S-100 extension PC 
board which plugs into the motherboard, 12 card guides, and 
all brackets and hardware needed for complete assembly. Just 
add required number of S-100 connectors 

In addition to six S-100 cards, Level "C" will also support 
an optional test socket that allows you to perform tests and 
maintenance on both sides of any individual S-100 card, under 
actual operating conditions. (You won't need Level "C" unless 
you are planning to use 3 or more S-100 cards with your 
Explorer/85.) 

Level "D" Specifications 

Level "D" provides 4k or RAM, power supply regulation, 
filtering decoupling components and sockets to expand your 
Explorer/85 memory to 4k (plus the original 256 bytes located 
in the 8155A). 

The 21 14 static RAM is organized as 1024 words by 4-bits 
using N-channel Silicon-Gate MOS technology and can be 
located anywhere from 0000 to EFFF in 4k blocks. 
Level "E" Specifications 

Level "E" adds sockets for 8k of EPROM to use the popular 
Intel 2716 or theTl 2516. It includes all sockets, power supply 
regulator, heat sink, filtering and decoupling components. 
Sockets may also be used for soon to be available RAM IC's 
(allowing for up to 12k of onboard RAM). 
Order A Coordinated 
Explorer/65 Applications Pak! 

Experimenter's Pak (SAVE $12.50)— Buy Level "A" and Hex 
Keypad/Display for $199.90 and get FREE Intel 8085 user's 
manual plus FREE postage& handling! 
Student Pak (SAVE $24.45)— Buy Level "A," ASCII Key- 
board/Computer Terminal, and Power Supply for $319.85 and 
get FREE RF Modulator plus FREE Intel 8085 user's manual 
plus FREE postage & handling! 

Engineering Pak (SAVE $41.00)— Buy Levels "A," "B," 
"C," "D," and "E" with Power Supply, ASCII Keyboard/ 
Computer Terminal, and six S-100 Bus Connectors for $514.75 
and get 10 FREE computer rrade cassette tapes plus FREE 
8085 user's manual plus FREE postage & handling! 
Business Pak (SAVE $89.95)— Buy Explorer/85 Levels "A," 
"B," and "C" {with cabinet), Power Supply, ASCII Key- 
board/Computer Terminal (with cabinet), 16k RAM, 12" 
Video Monitor, North Star 5-1/4" Disk Drive (includes North 
Star BASIC) with power supply and cabinet, all for just 
$1599.40 and get 10 FREE 5-1/4" minidiskettes ($49.95 value) 
plus FREE 8085 user's manual plus FREE postage & handling! 

Continental U.S.A. Credit Card Buyers Outside Connecticut 

CALL TOLL FREE 800-243-7428 

To Order From Connecticut Or For Technical 
™~ Assistance, Etc. Call (203) 354-9375 | 

sonalized disk operating system— just m 
plug it in and you're up and running!), I 
$699.95 plus $5 p&h. 

□ Power Supply for North Star Disk I 
Drive, $39.95 plus $2 p&h. 
D Deluxe Case for North Star Disk I 
Drive, $39.95 plus $2 p&h. 
D Experimenter's Pak (see above), I 
$199.90 postpaid. 

D Student Pak (see above), $319.85 1 
postpaid. 

G Engineering Pak (see above), | 
$514.75 postpaid. ■ 

□ Business Pak (see above), $1599.40 1 
postpaid. 



D Deluxe Steel Cabinet for ASCII 
Keyboard/Terminal, $19.95 plus $2.50 
p&h. 

□ Power Supply Kit ( ± 8V @ 5 amps) 
in deluxe steel cabinet, $39.95 plus $2 
p&h. 

D Cold Plated S-100 Bus Connectors, 
$4.85 each, postpaid. 

□ RF Modulator Kit (allows you to 
use your TV set as a monitor), $8.95 
postpaid. 

□ 16k RAM Kit (S-100 Board expands 
to 64k), $199.95 plus $2 p&h. 

□ 32k RAM Kit, $329.95 plus $2 p&h. 
D 48K RAM Kit, $459.95 plus $2 p&h. 
D 64k RAM Kit, $589.95 plus $2 p&h. 
D 16k RAM Expansion Kit (to expand 
any of the above up to 64k), $139.95 
plus $2 p&h each. 

D Intel 8085 cpu User's Manual, $7.50 
postpaid. 

D Special Computer Grade Cassette 
Tapes, $1.90 each or 3 for $5, postpaid. 
D 12" Video Monitor (10 MHz band- 
width), $139.95 plus $5 p&h. 
D North Star Double Density Floppy 
Disk System (One Drive) for Explorer/ 
85 (includes 3 drive S-100 controller, 
DOS, and extended BASIC with per- 



Total Enclosed $ 1 

(Conn. res. add sales tax) By — 

D Personal Check D M.O. /Cashier's I 

Check □ Visa □ Master Charge | 



(Bank #_ 



Signature . 
Print 
Name 



_£xp. Date _ 



City. 



_Zip„ 



D Send Me Information 



Circle 280 on inquiry card. 



September 1979 © BYTE Publications Inc 87 




Circle 141 on inquiry card. 

16K Static RAM 
Boards for the < 
SS-50 Bus ^ 

• Gold bus connectors 

• 4 separate 4K Blocks 

• Individual Addressing, 
Write Protect, and Enable/ 
Disable for each block Memories. . . 

s 298 13 

As above with 

Sockets and 

Software 

control 

features. 

s 368 16 

All GIMIX memory boards are assembled, 

Burnt-ln for 2 weeks, and tested at 2 MHz. 

Add $32.00 for 250 ns parts 



8K PROM BOARD $98.34 
2708s $7.90 each 

SS 50 BUS 80 x 24 
VIDEO BOARD 




ill 



TXT SgJ 



With hardware scrolling, x-y addressable cursor and 
multiple character generators. It includes a TMS 2716 
EPROM that contains a full 128 upper and lower case 
ASCII character set with true descenders; plus a socket 
for another TMS 2716 for an optional 128 character set; 
plus 2K of RAM for user-defined programmable 
character sets. This gives the user the ability to create 
his own heiroglyphics, alphabet, graphic elements, etc., 
and store them on PROM, disk, or tape. 

The user can choose and intermix 384 different 
characters from any or all of the character generators 
and display up to 256 at one time, normally or inversely, 
and at full or half intensity, at any location on the 
screen. Contiguous 8x10 character cells permit solid 
lines and connecting patterns with user definable 
graphic elements. 

It is addressable to any 2K boundary. GHOSTable ad- 
dressing allows multiple boards at the same address, 
making it ideal for multi-user applications. The available 
software includes a GMXBUG video based 3K ROM 
monitor, stand alone driver routines, and a program to 
create user defined characters. 

DELUXE VERSION $458.76 

Other Video Boards from $198.71 




16K SYSTEMS $1294.29 

Includes: Mainframe cabinet, mother 

board, power supply, fan, CPU, 16K static 

RAM, and choice of 1/0 card. 

Other packages available. 

Add $10. handling charge on orders under $200. 



inc. 



Gimix 

1337 WEST 37th PLACE 
CHICAGO, ILLINOIS 60609 
(312) 927-5510 • TWX 910-221-4055 

The Company that delivers. 

Quality Electronic products since 1975. 



AWG 


Diameter (mm) 


Ohms per 1000m 


Current Capacity (Amperes) 


10 


2.6 


3.3 


26 


12 


2.0 


5.2 


16 


14 


1.6 


8.3 


10 


16 


1.3 


13 


6 


18 


1.0 


21 


4 


20 


0.81 


33 


2.5 


22 


0.64 


53 


1.6 


24 


0.51 


84 


1.0 


26 


0.40 


135 


0.6 


28 


0.32 


214 


0.4 


30 


0.25 


341 


0.2 



Table 1: Approximate values for various American Wire Gauge (AWG) sizes of copper 
wire. 



can be read from the same side of the 
board. Run the wires in an orderly 
manner. I prefer to mount com- 
ponents like resistors, transistors, etc, 
slightly off the board. This improves 
the heat transfer, and makes it easier 
to slip in a probe for testing. Com- 
ponents that weigh 0.5 ounces or 
more should be mechanically 
mounted to the board. A little epoxy 
or silicon rubber works wonders for 
mounting these components. 

Properly stripping wire is a 
dichotomy. First, the insulation 
should be cut and removed. Second, 
the wire should not be cut. (If strand- 
ed wire is used, a nick will cause only 
a few strands to break.) With prac- 
tice, you can strip the insulation 
without cutting the wire. Try cutting 
slowly through a wire. Notice the dif- 
ference in the feel between the insula- 
tion and wire. Now cut off the wire 
and start again with a clean end. Cut 
down until the wire is felt, then relax 
the stripper slightly. Now rotate the 
wire 45° and again squeeze a bit. This 
will cut the insulation all the way 
around, not just where the stripper 
teeth cut the deepest. Be sure to open 
the stripper slightly and pull the in- 
sulation off the wire. With practice, 
you can learn not to nick the wire. 
The secret is to stop cutting just 
before the cutter reaches the wire. A 
firm pull will usually break off the re- 
maining insulation. If you still nick 
the wire, take heart, you have much 
company. 

Table 1 gives the American Wire 
Gauge (AWG) size, the approximate 
diameter, ohms per 1000 meters, and 
current carrying capability of copper 



wire. Try to use a number of wires of 
different colors and gauges. This not 
only matches the current capability 
with the load, but also makes it easier 
to trace wires. 

Finally, some words on safety: be 
sure that you have a stand for your 
iron; always wear shoes and safety 
glasses; and try not to flick solder on 
anything important. When cutting 
wires, hold the cutter so that the 
pieces fly away from you. To avoid 
potentially lethal shocks, it is best to 
have a rubber mat beneath your feet 
and stool. 

By following these rules and tech- 
niques, almost anyone can learn to 
solder well.H 







"WE WILL RETURN TO OUK PROS^M « JU57" -1 MOMENT, BUT' 
FlRST ft MESSAGE ffX». OUR SPONSOR, ' 



88 



September 1979 © BYTE Publications Inc 



POWER-ONE 
D.C. POWER SUPPLIES 

Now available for small systems applications 

Power-One, the leader in quality open-frame power supplies, now offers a complete line of single, dual, 
and triple output models for small computer systems. Also available are special purpose models for 
Floppy Disk and Microcomputer applications. 

Below are just a few popular examples of the over 90 "off the shelf" models now available from stock. 



SINGLE OUTPUTS 
LOGIC POWER SUPPLIES 

• 56 "off the shelf " 
models 

•2Vto250V,0.1Ato40A 

• ± .05% regulation 

• 115/230 VAC input 



5V@3A,w/OVP 




HB5-3/OVP 
$24.95 single qty. 



5V@ 12A,w/OVP 




HD5-12/OVP 
$79.95 single qty. 



5V @ 40A, w/OVP 



«tiv 



m 




SK5-40/OVP 
Switching Model 
$250.00 single qty. 



FLOPPY-DISK SERIES 

• 8 "off the shelf" 
models 

• Powers most popular 
drives 

• Single/dual drive 
applications 

• 2-year warranty 



5V @ 0.7A, w/OVP /l/Jfr,. 
1.1A/1.7APK*^W 



12V 




5V@ 1A, w/OVP 
-5V@0.5A, w/OVP 
24V @ 1.5A/1.7APK 



5V @ 2.5A, w/OVP 
-5V@0.5A, w/OVP 
24V @ 3A/3.4A PK 





CP340 

For one 5.25" Media Drive 

$44.95 single qty. 



CP205 

For one 8.0" Media Drive 

$69.95 single qty. 



CP206 

For two 8.0" Media Drives 

$91 .95 single qty. 



12V/15V 



DUAL OUTPUT MODELS 

• 15 "off the shelf" 
models 

• ±5Vto ±24V, 0.25A 
to6A 

• I.C. regulated 

• Full rated to +50°C 




5V @ 2A, w/OVP 
9-15V@0.5A 



±12V 
±15V 



1.7Aor 
1.5A 





HAD12-.25/HAD15-.25 
$32.95 single qty. 



HAA512 

$44.95 single qty. 



HBB15-1.5 
$49.95 single qty. 



TRIPLE OUTPUT 
MODELS 

• 10 "off the shelf" 
models 

• 5V plus ± 9V to 
± 15V outputs 

• Models from 16W to 
150W 

• Industry standard size 



5V@2A, w/OVP 

± 9Vto ± 15V@0.4A 



5V@3A, w/OVP 
±12V @ 1Aor 
± 15V @ 0.8A 




5V@6A, w/OVP 
±12V@1.7Aor 
±15V@1.5A 





HTAA-16W 
$49.95 single qty. 



HBAA-40W 
$69.95 single qty. 



HCBB-75W 
$91. 95 single qty. 



&xsy$* 



NEW 79' CATALOG! 

Get Your FREE Copy Now! 

Phone us direct or circle the reader service 
number below. 



& 



oeui 



%L&* 




power-one 




D.C. POWER SUPPLIES 



Power One Drive • Camarillo, CA 93010 • (805) 484-2806 • TWX 910-336-1297 



Circle 309 on inquiry card. 



BYTE September 1979 89 



Software / 

with / Manual 
Manual/ Alone 

DIGITAL RESEARCH 

D CP/M* Floppy Diskette Operating System — 

Packages supplied on diskette complete with 8080 as- 
sembler, text editor, 8080 debugger and various utilities 
plus full documentation. CP/M available configured for 
most popular computer/disk systems including: North 
Star Single, Double or Quad density, Altar 8" disks, 
Helios II, Exidy Sorcerer, Vector MZ, PolyMorphic 
8813t* Heath H17t or H89f, TRS-80t, iCOM 3712 and 
iCOM Micro Disk plus many other configurations avail- 
able off the shelf $145/525 

□ MAC — 8080 Macro Assembler. Full Intel macro defini- 
tions. Pseudo Ops include RPC, IRP, REPT, TITLE, 
PAGE, and MACLIB. Z-80 library included. Produces 
Intel absolute hex output plus symbols file for use by SID 
(see below) $1 00/S1 5 

□ SID — 8080 symbolic debugger. Full trace, pass count 
and break-point program testing system with back-trace 
and histogram utilities. When used with MAC, provides 
full symbolic display of memory labels and equated 
values $85/$1 5 

□ TEX — Text formatter to create paginated, page- 
numbered and justified copy from source text tiles, di- 
rectable to disk or printer $85/$ 1 5 

Q DESPOOL — Program to permit simultaneous printing 
of data from disk while user executes another program 
from the console $50/$1 



(M-M^f^L. 



OM 



□ 



□ 



□ 



□ 



□ 



□ 



MICROSOFT 

Disk Extended BASIC — Version 5, ANSI compati- 
ble with long variable names, WHILE/WEND, chaining, 
variable length (He records S300/S25 

BASIC Compiler — Language compatible with Ver- 
sion 5 Microsoft interpreter and 3-10 times faster execu- 
tion. Produces standard Microsoft relocatable binary out- 
put. Includes Macro-80. Also linkable to FORTRAN-80 or 
COBOL-80 code modules S350/S25 

FORTRAN-80 — ANSI '66 (except for COMPLEX) 
plus many extensions. Includes relocatable object com- 
piler, linking loader, library with manager. Also includes 
MACRO-80 (see below) S400/S25 

COBOL-80 — ANSI 74 Relocatable object output. 
Format same as FORTRAN-80 and MACRO-80 
modules. Complete ISAM, interactive ACCEPT/DIS- 
PLAY, COPY, EXTEND S625/S25 

MACRO-80 — 8080/Z80 Macro Assembler. Intel and 
Zilog mnemonics supported. Relocatable linkable output. 
Loader, Library Manager and Cross Reference List 
utilities included $149/$15 

EDIT-80 — Very fast random access text editor for text 
with or without line numbers. Global and intra-line com- 
mands supported. File compare utility included S89/S15 



Software / 

with /Manual 
Manual/ Alone 

XITAN (software requires ZBO" CPU) 

□ Z-TEL — Text editing language. Expression evaluation 
iteration and conditional branching ability. Registers 
available for text and commands. Macro command 
strings can be saved on disk for re-use $69/$20 

□ ASM Macro Assembler — Mnemonics per Intel with 
Z-80 extensions. Macro capabilities with absolute Intel 
hex or relocatable linkable output modules. New version 
3 with added features S69/$20 

D LINKER — Link-edits and loads ASM modules 
S69/S20 

□ Z-BUG debugger — Trace, break-point tester. Supports 
decimal, octal and hex modes. Disassembler to ASM 
mnemonic set. Emulation technique permits full tracing 
and break-point support through ROM S89/S20 

□ TOP Text Output Processor — Creates page-numbered, 
justified documents from source text files . . . $69/$20 

□ A4 package includes z-tel, asm, linker, z-bug, 

TOP $299/$40 

EIDOS SYSTEMS 

□ KISS — Keyed Index Sequential Search. Offers com- 
plete Multi-Keyed Index Sequential and Direct Access file 
management. Includes built-in utility functions for 16 or 
32 bit arithmetic, string/integer conversion and string 
compare. Delivered as a relocatable linkable module in 
Microsoft format for use with FORTRAN-80 or COBOL- 
80, etc SS3S/$23 

□ KBASIC — Microsoft Disk Extended BASIC with all 
KISS facilities, integrated by implementation of nine 
additional commands in language. Package includes 
KISS.REL as described above, and a sample mail list 
program S995/S45 

MICROPRO C^^ 

D Super-Sort I — Sort, merge, extract utility as absolute 
executable program or linkable module in Microsoft for- 
mat. Sorts fixed or variable records with data in binary, 
BCD, Packed Decimal, EBCDIC, ASCII, floating, fixed 
point, exponential, field justified, etc. etc. Even variable 
number of fields per record! $225/$25 

□ Super-Sort II - 

only 

□ Super-Sort III — As II without SELECT/EXCLUDE 

$125/$25 

D Word-Star — Menu driven visual word processing sys- 
tem for use with standard terminals. Text formatting per- 
formed on screen. Facilities for text paginate, page 
number, justify, center, underscore and PRINT. Edit 
facilities include global search and replace, read/write to 
other text files, block move, etc. Requires CRT terminal 
with addressable cursor positioning $445/$25 



'/ 



Above available as absolute Drooram 
$175/$25 



Software / 

with /Manual 
Manual/ Alone 

D Word-Master Text Editor — In one mode has super- 
set of CP/M's ED commands including global searching 
and replacing, forward and backwards in file. In video 
mode, provides full screen editor for users with serial 
addressable-cursor terminal $1 25 $25 

SOFTWARE SYSTEMS 

□ CBASIC-2 Disk Extended BASIC — Non-interactive 
BASIC with pseudo-code compiler and runtime interpre- 
ter. Supports full file control, chaining, integer and ex- 
tended precision variables, etc $90/$15 



"CP/M is a trade name of Digital Research 
* Z80 is a trademark of Zilog, Inc. 
"WHATSIT? is a trademark of Computer 
Head ware. 



tCP/M for Heath, TRS-80 Model I and PolyMorphic 8813 are 
modified and must use especially compiled versions of system 
and applications software, 
tfPolyMorphic 8813 CP/M scheduled for September 15 release. 



STRUCTURED SYSTEMS GROUP 

D General Ledger — Interactive and flexible system 
providing proof and report outputs. Customization of COA 
created interactively. Multiple branch accounting centers. 
Extensive checking performed at data entry for proof, 
COA correctness, etc. Journal entries may be batched 
prior to posting. Closing procedure automatically backs 
up input files. All reports can be tailored as necessary. 
Requires CBASIC $899/$25 

□ Accounts Receivable — Open item system with 
output tor internal aged reports and customer-oriented 
statement and billing purposes. On-Line Enquiry permits 
information tor Customer Service and Credit depart- 
ments. Interface to General Ledger provided if both sys- 
tems used. Requires CBASIC $699/$25 

D Accounts Payable — Provides aged statements of 
accounts by vendor with check writing for selected in- 
voices. Can be used alone or with General Ledger and/or 
with NAD. Requires CBASIC $699/$25 

□ NAD Name and Address selection system — interactive 
mail list creation and maintenance program with output 
as lull reports with reference data or restricted informa- 
tion for mail labels. Transfer system for extraction and 
transfer of selected records to create new files. Requires 
CBASIC $79/$20 

D QSORT — Fast sort/merge program for files with fixed 
record length, variable field length information. Up to five 
ascending or descending keys. Full back-up of input files 
created S95/S20 

tRAHAM-DORIAN SOFTWARE 
YSTEMS 

D PAYROLL SYSTEM — Maintains employee master 
file. Computes payroll withholding for FICA, Federal and 
State taxes. Prints payroll register, checks, quarterly re- 
ports and W-2 forms. Can generate ad hoc reports and 
employee form letters with mail labels. Requires 
CBASIC. Supplied in source code $590/$35 

□ APARTMENT MANAGEMENT SYSTEM - Fi- 
nancial management system for receipts and security 
deposits of apartment projects. Captures data on vacan- 
cies, revenues, etc. for annual trend analysis. Daily report 
shows late rents, vacancy notices, vacancies, income 
lost through vacancies, etc. Requires CBASIC. Supplied 
in source code $590 $35 



Software for most popular 8080IZ80 computer disk systems 
including NORTH STAR, MICROPOUS, iCOM, DYNABYTE DB8I2, 
SD SYSTEMS, ALTAIR, EXIDY SORCERER, VECTOR MZ, 
8" IBM, HEATH H17 & H89, HELIOS, IMSAI VDP42 & 44, REX, 
POLYMORPHIC 8813' and OHIO SCIENTIFIC formats. 




90 BYTE September 1979 



Software j 

with /Manual 
Manual/ Alone 

□ INVENTORY SYSTEM - Captures stock levels, 
costs, sources, sales, ages, turnover, markup, etc. 
Transaction information may be entered for reporting by 
salesman, type of sale, date of sale, etc. Reports avail- 
able both for accounting and decision making. Requires 
CBASIC. Supplied in source code $590/535. 

D CASH REGISTER — Maintains files on daily sales. 
Files data by sales person and item. Tracks sales, over- 
rings, refunds, payouts and total net deposits. Requires 
CBASIC. Supplied in source code 5590/535 

MICRO FOCUS 

□ CIS COBOL — Version 3 is ANSI 74 subset with ex- 
tensions which offer powerful interactive screen format- 
ting and built in cursor control. Version 4 additionally oi- 
lers full level 1 ANSI for Nucleus, Table Handling, Se- 
quential Relative and Indexed I/O, Inter-Program Com- 
munication and Library 

Version 3, 5650/550 

Version 4, S850/S50 

□ FORMS — Interactive utility to create CIS COBOL 
source code to perform CRT screen handling in applica- 
tion programs. Supports full prompt text, protected fields 
and input validation against data type and range 

expected $1 50/$1 5 

When purchased with CIS COBOL $125/515 

OTHER 

D tiny C — Interactive interpretive system for teaching 
structured programming techniques. Manual includes full 
source listings $75/540 

D C Compiler — Supports most major leatures of lan- 
guage, including Structures, Arrays, Pointers, recursive 
function evaluation, linkable with library to 8080 binary 
output. Lacks data initialization, long & float type and sta- 
tic & register class specifiers. Documentation includes 
"C" Programming Language book by Kernighan & 
Ritchie $1 10/515 

□ ALGOL 60 Compiler — Powerful block-structured 
language featuring economical run time dynamic alloca- 
tion of memory. Very compact (24K total RAM) system 
implementing almost all Algol 60 report features plus 
many powerful extensions including string handling direct 
disk address I/O etc. Requires Z80 CPU . . . .$199/520 

□ Z80 Development Package — Consists of: (1) disk 
file line editor, with global inter and intra-line facilities; (2) 
Z80 relocating assembler, Zilog/Mostek mnemonics, 
conditional assembly and cross reference table 
capabilities; (3) linking loader producing absolute Intel 
hex disk tile $95/$20 

□ Z80 Debugger — Trace, break and examine registers 
with standard Zilog/Mostek mnemonic disassembly dis- 
plays. Facilities similar to DDT. $35 when ordered with 
Z80 Development Package $50/$1 

D DISTEL — Disk based disassembler to Intel 8080 or 
TDL/Xitan Z80 source code, listing and cross reference 
files. Intel or TDL/Xitan pseudo ops optional. Runs on 
8080 $65/$10 

□ DISILOG - A DISINTEL to Zilog/Mostek mnemonic 
files. Runs on Z80 only $65/510 

□ TEXTWRITER II — Text formatter to justify and pagi- 
nate letters and other documents. Special features in- 
clude insertion of text during execution from other disk 
files or console, permitting recipe documents to be 
created Irom linked fragments on other files. Ideal for 
contracts, manuals, etc. Also creates form letters in con- 
junction with a mail list file $75/510 

□ TEXTWRITER III — All the features of TW II plus gen- 
eration of table of contents, sorted index and handling of 
footnotes. TW II users may upgrade for $60. $125/$10 

□ WHATSIT?*** — Interactive data-base system using 
associative tags to retrieve information by subject. Hash- 
ing and random access used for fast response. Requires 
CBASIC $125/525 

□ XYBASIC Interactive Process Control BASIC — Full 
disk BASIC leatures plus unique commands to handle 
bytes, rotate and shift, and to test and set bits. Available 
in Integer, Extended and ROMable versions. 

Integer Disk or Integer ROMable $295/525 

Extended Disk or Extended ROMable 5395/525 



Lifeboat Associates 

2248 Broadway, N.Y., N.Y. 10024 
(212)580-0082 Telex; 668-585 



Software 



□ manual alone 



□ manual alone 



□ manual alone 



□ Check DU.P.S. COD □ Visa □ Master Charge 



Exp. Date 



Shipping 



$1.00 for C.O.D. 



Total 



Account # 




Signature 



My computer configuration (specifying di sk system): 



Name 



Address (No P.O. Box) 



City 



State 



Zip 



Price 



Orders must specify 
disk systems and 
formats: e.g. North 
Star single or double 
density, IBM single or 
2D/256, Altair, Helios 
II, Micropolis Mod I or 
II, 614* soft sector 
(Micro iCOM/SD 
Systems Dynabyte), etc. 

Add $1/item shipping 
($2 min.). Add $1 
additional for UPS 
C.O.D. 

Manual cost 
applicable against 
price ol subsequent 
software purchase. 

The sale of each 
propriety software 
package conveys a 
license lor use on one 
system only. 



Software / 

with /Manual 
Manual/ Alone 

D SMAL/80 Structured Macro Assembled Language — 
Package of powerful general purpose text macro proc- 
essor and SMAL structured language compiler. SMAL is 
an assembler language with IF-THEN-ELSE, LOOP- 
REPEAT-WHILE, DO-END, BEGIN-END constructs 
575/51 5 

D Selector II — Data Base Processor to create and main- 
tain single Key data bases. Prints formatted, sorted re- 
ports with numerical summaries. Available for Microsoft 
and CBASIC (state which). Supplied in source code 
5195/520 

□ Selector III — Mufti (i.e., up to 24) Key version of Selec- 
tor II. Comes with applications programs including Sales 
Activity, Inventory, Payables, Receivables, Check Regis- 
ter, Expenses. Appointments, and Client/Patient. Re- 
quires CBASIC. Supplied in source code $295/520 

Enhanced version for CBASIC-2 $345/520 

□ CPM/374X Utility Package — Has full range of 
functions to create or re-name an IBM 3741 volume, dis- 
play directory information and edit the data set contents. 
Provides full file transfer facilities between 3741 volume 
data sets and CP/M files $195/510 

D Flippy Disk Kit — Template and instructions to modify 
single sided 5V4" diskettes for use of second side in sin- 
gled sided drives $12.50 

□ BASIC Comparison — A comprehensive features 
and performance analysis of five 8080 disk BASIC lan- 
guages — CBASIC, BASIC-E, XYBASIC, Microsoft Disk 
Extended BASIC, and Xitan's Disk BASIC. Itemizes re- 
sults of 21 different benchmark tests for speed and accu- 
racy and lists instructions and features of each BASIC 
(send 20? S.A.S.E.) FREE 




Lifeboat Associates 

2248 Broadway 
New York, N.Y. 10024 




"The Software Supermarket is a trademark ol Lifeboat Associates 



BYTE September 1979 



91 



Blubs and Newsletters 



Washington DC 
Computer Club 

The Washington Amateur 
Computer Society (WACS) 
is an organization dedicated 
to personal computing. 
They are organized to pro- 
vide a forum for the com- 
puter hobbyist and student 
of computing science. The 
Society meets on the last 
Friday of each month in the 
1st floor lecture hall in 
Keane Hall on the campus 
of the Catholic University of 
America. The meetings start 
at 7:30 PM 

JWAC, the club's news- 
letter, is published for Socie- 
ty members and exchange 
with other hobby organi- 
zations. The newsletter is 
primarily an electronics 
journal. Annual dues have 
been set at $3.50 per year to 



cover the cost of 1st class 
postage for the journal and 
to defray the expenses of 
exchanging correspondence 
with other personal com- 
puting organizations. Non- 
members may subscribe to 
the journal at the rate of $5 
per year. WACS is inter- 
ested in exchanging news- 
letters with other organiza- 
tions to further the inter- 
change of hobbyist infor- 
mation. Contact Washington 
Amateur Computer Society, 
c/o 4201 Massachusetts 
Ave, #168, Washington DC 
20016. 



Cromemco User 
Systems and 
Software Pool 



Cromemco User, Systems 
and Software Pool is an 



HARD DISC 
FOR S100 MICROS 

The XCOMP DCF-10 Disc Controller pro- 
vides the OEM with a high performance, 
low.cost interface forfixed and removable 
(2315 or 5440) cartridge disc drives. The 
DCF-10 is currently supported by two 
operating systems. For information or 
manuals, contact XCOMP. 




XCOMP 

INCORPORATED 

9915-A Businesspark Ave., San Diego, CA 92131 • (714) 271-8730 



independent group for users 
of Cromemco computers. 
Board owners are also 
welcome. The purpose of 
CUssP is the exchange 
among users of Cromemco 
hardware and software of 
operating notes, bugs and 
their fixes, evaluation of 
hardware and software, user 
written software, and other 
announcements relating to 
Cromemco and associated 
products. 

The 1st volume of 3 
newsletters included articles 
on changes in 16 K byte 
BASIC, CDOS I/O (input/- 
output) drivers, disk sectors 
and clusters, hardware 
modifications, etc. This 
volume is available for $10 
in the US, Canada, and 
Mexico; and $12 in US 
funds for airmail delivery 
outside these regions. 
Membership with the 2nd 
volume is the same price as 
the 1st. There is also a 
special rate of 3 volumes (9 
issues) for $25 in the US, 
Canada, and Mexico and 
$30 elsewhere. 

Contact Cromemco User, 
Systems and Software Pool, 
POB 784, Palo Alto CA 
94302. 



Computer Graphics 

Letter Published 

by Harvard 

Readers of the new Har- 
vard Newsletter on Com- 
puter Graphics will be able 
to keep abreast of computer 
graphics in all its myriad 
ramifications. The newsletter 
monitors important commer- 
cial, technological, and pro- 
duct developments, as well 
as market, application, and 
learning opportunities. 
Among the regular depart- 
ments are News and Trends, 
Products, Markets, Applica- 
tions, R and D, Conferences 
and Seminars, Companies, 
Business and Financial, and 
State-of-the-Art Technology. 
The newsletter will be 



published twice a month. 

The content will encom- 
pass management and statis- 
tical graphics, computer 
graphic-aided design, 
engineering and manufac- 
turing, image processing, 
and automated cartography, 
plus other related areas. 
Trends in these areas, 
whether applied to big or 
small computers, stand- 
alone terminals, timesharing 
networks, users, vendors, 
will be followed. Readers 
will also learn where to ob- 
tain further information on 
the material covered. 

The subscription fee for 1 
year is $125; a 9-issue trial 
subscription is available for 
$45. Airmail outside of 
North America is $19.50 for 
1 year or $9.75 for the trial. 
Contact William Nisen, Har- 
vard University, Laboratory 
for Computer Graphics, 520 
Gund Hall, Cambridge MA 
02138. 



Akron Ohio 
Digital Group 

The Akron Digital Group 
meets on the 4th Wednesday 
of each month at 7 PM at 
the Kenmore Public Library, 
2200 14th St SW, Akron 
OH. The club programs are 
aimed toward the small 
systems hobbyist with tips 
on programming and hard- 
ware application. Micro- 
processor classes are 
planned for the fall. Contact 
Lou Laurich, Akron Digital 
Group, 107 7th St NW, 
Barberton OH 44203. 



TRS-80 Publication 

Insiders: The TRS-80 
Hardware Journal with 
Machine Software is a 
publication for any TRS-80 
owner or user interested in 
more than BASIC. Both 
beginners and experts will 
find articles on machine 



92 September 1979 © BYTE Publications lnc Circle 393 on inquiry card. 



language programming, 
hardware modifications, and 
other computer languages. 
Published since June of 
1978, articles have described 
the differences in Level II 
read-only memories, how to 
get sound effects and music 
without a hardware 
modification, new languages 
for the TRS-80, and many 
other subjects. Regular 
features include a column 
which reviews various 
printers, the Disc File which 
covers the latest in DOS and 
compatible drives, a Dear 
Aunt TRiSh question and 
answer column, and learning 
machine language with Level 
II. 

A new section of the jour- 
nal will cover several of the 
new languages for the 
TRS-80. Future issues will 
include regular features on 
FORTRAN, FORTH, and 
other languages. Also, there 
will be regular articles on 
CP/M, reviews of various 
commercially available pro- 
grams, and more on both 
Level II and DOS. 

Subscriptions are available 
for 6 issues through Com- 
puter Cablevision, 2617 
42nd St NW, Suite 2N, 
Washington DC 20007. 



New PET Users Group 

Forming in Washington 

and Oregon 

Individuals interested in 
forming a PET Users Group 
in the Oregon and 
Washington area should 
contact NW PET Users 
Group, c/o John F Jones, 
2134 NE 45th Ave, Portland 
OR 97213. 



COSMAC Users Group 
Active Again 

After several unavoidable 
delays, the COSMAC Users 
Group is back in full opera- 
tion and The 1802 
Peripheral newsletter is 
being published on a mon- 
thly basis. Information 
about the group may be 
obtained by writing to 



Patrick Kelly, Director, 
COSMAC Users Group, 
POB 7162, Los Angeles CA 
90022. Please include a 
stamp with your inquiry. 



New Speechlab Users 
Group Formed 

Heuristics Inc, manufac- 
turer of Speechlab (a speech 
recognition unit for the 
Apple and all S-100 bus 
computers), has announced 
the formation of a users 
group. The users group 
requests that all interested 
Speechlab users send their 
unique uses of the hardware 
or software to Tom Larson, 
Director of Sales, Heuristics 
Inc, 900 N San Antonio Rd, 
Los Altos CA 94022. A 
directory of users and appli- 
cations will be published at 
a later date. 



Aim-65 Newsletter 

The Target is a bi- 
monthly newsletter for 
owners or prospective 
owners of Aim 65 systems. 
The subscription rate is $5 
for 1 year. Contact Custom- 
Tronics, POB 4310, Flint MI 
48504. 



Solano TRS-80 
Users Club 

The Solano TRS-80 Users 
Club is an informal group 
that gets together to discuss 
mutual problems and exper- 
iences. Their meetings are 
held every 3rd Thursday 
starting July 5th at Owens- 
Illinois, 2500 Huntington 
Dr, Fairfield CA. Contact 
Dave or Steve Irwin, 550 
Marigold Dr, Fairfield CA 
94533, or call (707) 
422-3347. 



The Tulsa 
Computer Society 

The Tulsa Computer 
Society meets the last Tues- 
day of every month at 7:30 



PM. The meeting place is 
the Tulsa Vocational- 
Technical School seminar 
room at 3420 South 
Memorial Dr (behind 
Edison's Department Store). 
Membership in TCS is $6 
annually and includes a 1 
year subscription to the 
club's newsletter, The I/O 
Port. Contact The Tulsa 
Computer Society, POB 
1133, Tulsa OK 74101. 



Wichita Valley 

TRS-80 Users Group 

Sustains Computer 

Loss in 

Recent Tornado 

In the recent tornado 
which wreaked unholy 
havoc on our city, many of 
us in the Wichita Valley 
TRS-80 Users Group lost 
our computers, our tape and 
disk library of software, and 
our library of computer 
books and periodicals. Even 
our club's library of soft- 



ware and publications was 
destroyed. 

We all have plans to 
replace our personal com- 
puters and software, but at 
this time I am particularly 
interested in trying to help 
our club replace its loss. 

Any club, publisher, soft- 
ware producer, or individual 
who wishes to do so, may 
contribute noncash items, 
such as software, back issues 
of computer publications, 
and books on computers. 

Our address is the Wichita 
Valley TRS-80 Users Group, 
POB 4391, Wichita Falls 
TX 76308. 

Thank -you, our club will 
be grateful. 

J Wesley B Taylor 
Club Secretary 

Although this letter cer- 
tainly speaks for itself, it is 
our sincere hope that you or 
your group will seriously 
consider contributing non- 
cash computer related items 
to this needy organization.* 



computer mart of new jersey 
computer mort of Pennsylvania 



the 

microcomputer 

people® 

Computers don't moke a 
computer store, PEOPLE do. Our 
people hove been involved with 
microcomputers since day one. 
We offer experience and 
expertise unparalleled in the 
microcomputer industry. Whether 
you are in the market for o 
complete system, peripherals, 
custom software, service, or just 
some friendly advice; there simply 
is no other place to go. 



Computer Mart of Now Jonoy 

501 Rout* 27 
iMlln. NJ 08800 
(201) 280-0600 



STOKE HOURS 
Tum. - Sat. 1 0am - 6p 
Tuai. Thun. 'till 9p 
CLOSED MONDAYS 



Computar Mart of P»nnjy Ivor 

330 DoKalb Pill* 

King of Prussia, PA 19406 

(213) 263-2380 



Circle 66 on inquiry card. 



September 1979 © BYTE Publications Inc 



93 



^MINIMAX 



C 0MP U 



"FULLY INTEGRATED COMPUTER SYSTEM" 




MINIMAX SERIES COMPUTER 



THE MINIMAX SERIES WAS DESIGNED 

TO OFFER THE MARKET MINICOMPUTER 

CAPABILITIES AT MICROCOMPUTER PRICES. 

COMPARE THE CAPABILITIES & PRICE! 

CONTACT NEECO FOR FULL SPECS - FREE MINIMAX MANUAL. 



MEET THE 
MINIMAX COMPUTER THE MINIMAX SERIES computer was designed by industry professionals. 

frfffV KsKJ COMPARE THE PRICE AND FEATURES TO ANY OTHER COMPUTER IN ITS CLASSI 




MINIMAX I - .8 MEGABYTE 
ON LINE MINIFLOPPY STORAGE 
MINIMAX II - 2.4 MEGABYTE 
ON LINE 8" FLOPPY STORAGE 



MINIMAX I - 
MINIMAX II - 



$4495 
$5995 



•THE MINI MAX SERIES COMPUTER IS AN INTEGRATED. COMPACT UNIT CONTAINING THE CPU. DUAL DENSITY DISK STORAGE. 12 
INCH CRT, AND FULL STYLE KEYBOARD, WITH SEPARATE NUMERIC ENTRY PAD. ALL KEYS (INCLUDING CURSOR) WITH FULL 
REPEAT • HYBRID 2 MEGAHERTZ 6502 CPU • 108K SYSTEM RAM (48K USER) • FASTEST FLOPPY DISK ACCESS (24K LOADS IN 4.2 
SECONDS) • 16K ROM CONTAINS COMPUTHINK BASIC (AN EXTENDED MICROSOFT BASIC) WITH EXTENDED PRECISION, DOS 
INCLUDES COMPLETE FILE I/O WITH FULL RANDOM ACCESS, COMPLETE MONITOR WITH DEBUG & TRACE, AND TINY 6502 
ASSEMBLER • COMPLETE HIGH RESOLUTION GRAPHICS WITH INDIVIDUAL DOT (240x512) POINT SCREEN ADDRESSABILITY • 
FULL SCREEN TEXT EDITING WITH OVERWRITE. INSERTION OR DELETION • SPLIT SCREEN/WINDOW MODES • INDIVIDUAL 
FIELD EDITING WITH FIELD PROTECT AND AUTO SKIP TO NEXT FIELD • DISK STORAGE SYSTEM TRANSFERS 6K PER SECOND 
WITH AUTO VERIFY AND PARITY CHECK • 12 INCH CRT-64 CHARACTERS BY 30 LINES. UP TO THREE PROGRAMMABLE 
CHARACTER FONTS FOR LANGUAGES OR SPECIAL CHARACTERS • • • SWITCHABLE 1 10 OR 220V OPERATION • • • • HYBRID 
CPU IS MICROPROGRAMMABLE WITH 64 USER DEFINABLE OPCODES. CHOICE OF 800K OR 2.4 MEGABYTE DISK STORAGE • FULL 
SERIAL RS-232C PORT WITH PROGRAMMABLE BAUD RATES AND MODEM CONTROL SIGNAL • DEDICATED DISK PORT • 
PRINTER PORT SUPPORTS PARALLEL COMMERCIAL PRINTERS • 24 PIN I/O USER PORT • PAGEMATE DATABASE 
AVAILABLE • PLM COMPILER AVAILABLE • BUSINESS PACKAGES AVAILABLE • COMPLETE DIAGNOSTICS & SCHEMATICS 
INCLUDED • COMPLETE USER MANUAL INCLUDED 

SPECIAL DEALER PRICING AVAILABLE ON DEMONSTRATION 

MINIMAX AND SOFTWARE PACKAGES TO QUALIFIED 

SELECTED DEALERS. CONTACT NEECO FOR INFO. 



PRINTER NOT 
INCLUDED IN PRICE 



THE MINIMAX WAS DESIGNED AND IS MANUFACTURED BY COMPUTHINK 
COMPUTER CORP. DISTRIBUTED IN EUROPE AND THE EASTERN U.S. BY NEECO. 



IN ADDITION TO HARDWARECAPABILITIES THAT ARE UNMATCHED IN THE INDUSTRY, THE MINIMAX 
COMPUTER SUPPORTS A COMPLETE DATA BASE SYSTEM (PAGEMATE), CONTAINING FULL 
STATISTICAL, SORTING, AND EDIT FUNCTIONS. A PLM COMPILER IS AVAILABLE, FULL BUSINESS 
SUPPORT SOFTWARE IS AVAILABLE AND MORE!— FULL DEALER SUPPORT IS AN IMPORTANT 
PART OF OUR MARKETING. CONTACT NEECO FOR FURTHER INFORMATION. 



THE MINIMAX IS NOW AVAILABLE FOR QUANTITY DELIVERY. DOMESTIC DEALERSHIPS AVAILABLE. 

EUROPEAN DISTRIBUTORSHIPS/DEALERSHIPS AVAILABLE TO QUALIFYING COMPANIES WITH 

SUPPORT CAPABILITIES. SOFTWARE HOUSES AND OEM INQUIRIES INVITED. CONTACT NEECO. 



NEECO 



NEW ENGLAND ELECTRONICS CO., INC. 

679 HIGHLAND AVE., NEEDHAM, MA 02194 

MON-FRI, 9:00-5:30, E.S.T. 



(617)449-1760 



TELEX 951021, ANSWERBACK "NEECO' 



94 BYTE September 1979 



Circle 281 on inquiry card. 



NEECO 



PET 2001 — 32K 




PROUDLY ANNOUNCES THE NEWEST 

PET MICROCOMPUTERS BY COMMODORE! 

The PET™ is now a truly sophisticated 

Business System with the 
announcement of these Peripherals. 



"he PET'", incwjiar.-ilml -.v-th ine I tunny D.sk air] Printer 
makm an ideal Business system for most crotessronai 
and sfiuciatoct Mils medicine taw, denial resesrcti 
tnginaering loolmaking. ptintmc; education, energy cnn 
sorvaien, etc The PET™ Business System as a 
n!ati,i(jf;mGnr io:;1 (tolivL'rs >ntar million 10 all levels of 
Business previously aiid'iiaUie only win cquipmeni 
nany limosmoicc(X;nsi«e Tun PET 1 * Business 
System is ore Of Ine most cost OfftOOrt Dusness ion's 



lixi.iy it offers ci '.'jiiI' 1 r.iniii: ot ;jr,)pi.i-;ikKis tram logging 
m;ina;iei'n(ir,t si(,iii>(iy in major rcGrpcrationsioarrjiirionii 
accounts and inventory control of small DuS'nessf.'ij Here 
are |usl a tew ot Hie cost- saving uses in ihe cO'poratinn 
prolessionai office 01 small business slock connol 
purchasing. irj:e(:.-isliiH| manuiadiiring costing. customer 
records, mailing hsls. etc The PET ". Floppy Disk and 
Punier a comoatiDie business system at a reasonable 
p/ice — Take a closer too-! at mese Fcrinne-ais 



LARGE TYPEWRITER KEYBOARDS NOW AVAILABLE! 



PRODUCT DESCRIPTION 

PET 2001— 4K 4K RAM 

PET 2001— 8K 8K RAM 

PET 2001 — 16KN (Large Keys)16K RAM* 
PET 2001— 32KN (Large Keys)32K RAM 



PET 2023 PRINTER 
PET 2022 PRINTER 
PET 2040A 
PET 2040 
PET C2N 



ROLL FEED 

TRACTOR/ROLL 

SINGLE FLOPPY 

DUAL FLOPPY* 

2nd Cassette 

"The 16K/32K (large keyboard) units do not include a cassette drive. Order C2N Cassette 
2040 Floppy Drive requires a 16K or 32K unit. 8K RAM Retrofit available July. 



PRICE 
$ 595 

$ 795 
$ 995 
$1295 
$ 850 
$ 995 
$ 895 
$1295 
$ 100 



AVAILABILITY 

IMMEDIATE 
IMMEDIATE 
IMMEDIATE 
IMMEDIATE 
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IMMEDIATE 
JUNE/JULY 
IMMEDIATE 
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ALL UNITS ARE FULLY TESTED BYNEECO BEFORESHIPMENT. ALL PET'S ARE 
WARRANTEED (BY NEECO) FOR 1 FULL YEAR! NEECO IS A FULL CUSTOMER- 
ORIENTED BUSINESS. PLEASE CALL FOR ADDITIONAL INFORMATION. ALL 
UNITS ARE IN STOCK & READY TO SHIP. FULL SOFTWARE AVAILABLE! 




FOR 8K PETS 

(small keyboards) 

.4 Megabytes of Disk 

Storage for8K PETS! 

(Requires Expandamem) 

400K-8S DISK SYSTEM INCLUDES RANDOM 

ACCESS IN DOS-LOADS 20K IN 4 SECONDS! 

24K Expandamem Memory -525 $W QQC 

32K Er.pandamem Memory : -615 I fa*/ J 



COMPUTHINK .4 & .8 MEGABYTE DISK 
DRIVES FOR THE NEW 16/32K PETS! 

DISK SYSTEMS INCLUDE DISKMON OPERATING 
SYSTEM IN ROM AND INTERFACE TO 16/32 PETS! 

Dual Minifloppy Drives with 200K per diskette side for total 4O0K/80OK on line. 
800K model accesses all 4 diskette sides via dual read and write arm system 
Dual Dens'ty Hardware and DOS loads 20K (with verification) in 4 2 seconds complete 
DISKMON (DOS) adds 17 commands to BASIC including Random Access and printer support 
1 System comes complete wilh plug in internal board containing 8K RAM. DOS. and Disk Controller 
Hardwaie— BoiHd plugs directly onto internal memory expansion pins 

■ System does not utilize IEEE or USER Port, system functions directly from memory porl 
1 All DISKMON DOS commands reside interactively with BASIC— disk directory command and 

format command do not interfere with program in RAM -DOS command were designed for 
simplicity of use System was manufactured for heavy commercial use 
1 Sysiern installs completely in less than ten minutes immediately ready lor use 
'1295 and 'T 595 prices include all hardware. DOS. complete user manual, and demo.' utility diskette 

■ Available software includes PLM Compiler < s 250l. Relocatable Assembler ('70). Source-Editor 
Program t'70). Autolink Linking Loader C70). and a complete Database system (Pagemaie *495) 
Call or write lor complete product information and specifications— Usoi manual l 10. 

(PRODUCT AVAILABILITY IS AUG/SEPT— CALL FOR INFO) 

ALL 16/32K MODELS INCLUDE AN 400K-16N s 1295 

INTERNAL PLUG-IN INTERFACE 400K-32N M295 

BOARD CONTAINING DOS, 8K OF 800K-16N '1595 

RAM. AND CONTROLLER 800K-32N s 1595 



CALL OR WRITE FOR A FREE COPY OF OUR NEW JULY CATALOG! 

NEW CENTRONICS 730 PRINTER FOR PET! 

• NEWEST TECHNOLOGY FROM CENTRONICS • 50 CPS • 80 CHARACTER LINE 

• 10 CPI • 7x7 DOT MATRIX • HANDLES ROLL FEED, PIN FEED 

£ PAPER • UPPER & LOWER CASE— s 1099 PRICE INCLUDES 

— - INTERFACE TO IEEEPORT. AVAILABLE AUG/SEPT. 




$1099 



TRS-80 USERSI-THE 



MODEL 730 IS AVAILABLE FOR USE WITH 
THE TRS-80. PRICE 
INCLUDES CABLE 

only 



$ 995 



WECANNOTLISTALLOF OUR SOFTWARE AND HARDWARE PRODUCTS 
CALLOR WRITE FOR OUR*FREE*SOFTWARE/HARDWARE DIRECTORY 

ALL NEECO PETS CARRY A FULL ONE-YEAR NEECO WARRANTEE 



NEECO 



NEW ENGLAND ELECTRONICS CO., INC. 

679 HIGHLAND AVE., NEEDHAM, MASS. 02194 
MON. - FRI. 9:30 - 5:30, EST. 



(617)449-1760 

MASTERCHARGE OR VISA ACCEPTED 
TELEX NUMBER 951021, NEECO 



Circle 281 on inquiry card. 



BYTE September 1979 95 



The Nature of Robots 

Part 4: Looking for Controlled Variables 



William T Powers 

1138 Whitfield Rd 

Northbrook IL 60062 



In this last part of my series of 
articles, a simple experiment with a 
human subject will be attempted; an 
experiment that can be expanded 
almost indefinitely. All of the prin- 
ciples from the previous parts will be 
used. Before the experiment starts, 
note the following main points that 
have been established: 

• The behavior of an organism is not 
its output, but some consequence 
of its motor outputs acting 
together with unpredictable forces 
or other disturbances. 

• For a more or less remote conse- 
quence of motor outputs to be 
repeatable in a disturbance-prone 
world, the behaving system must 
sense the consequence, and act to 
keep it matching some static or 
dynamic reference condition. By 
definition, that makes the 
organism a control system. 

• Organisms acting as control 
systems control what they sense, 
not what they do. 

• What is controlled is what is 
sensed, even when the sensing in- 
volves one or more stages of real- 
time computations based on 
primitive sensory signals. 

• In a multiple-level control system, 
the higher levels act by varying the 
reference signals for lower-level 
systems. They control perceptions 
computed from many lower-level 
perceptions, some or all of which 
are controlled by the same lower- 
level systems. 

• If there are n degrees of freedom at 
one level of control, in principle n 
higher-level systems could act in- 
dependently and simultaneously 
by sharing the use of the lower- 
level systems. Any higher-level 



system acts by sending amplified 
copies of its error signal to many 
lower-level systems, each with the 
proper sign to achieve a negative 
feedback effect. Any lower-level 
system receives a reference signal 
that is the net effect of super- 
imposed higher-level output 
signals. This worked for a 2-level 
system with 3 control systems at 
each level; there is no limit, in 
principle, to the number of levels 
or the number of systems at each 
level. In practice, there is reason to 
anticipate finding hundreds of 
systems at a given level, but no 
more than 10 or 12 distinct levels 
in a human being. This will be 
commented on later. 

Abstract models and simulations 
are fine for conveying general ideas. 
However, if one does nothing but 
make models and simulations, it is 
easy to get involved in the math and 
engineering, and forget the real thing 
is there to be seen. Items described in 
the first 3 articles in this series repre- 
sent something real. Real organisms 
work much the same way control 
systems work. They do not work in 
any of the other ways that have been 
proposed over the centuries (as far as 
their behavior is concerned). I am not 
talking metaphorically. There are ex- 
cellent reasons to think that when the 
properties of organisms begin to be 
investigated in terms of control 
theory, hard data about the way we 
are organized will start to accumulate 
(up to a point, anyway). 

The experiment to be described in 
this article is so simple that it may 
look elementary. Nevertheless, it is 
the starting point for a new approach 
to exploring the organization of 



human beings. Most new ideas start 
by looking like old ones, but with a 
twist that leads in unexpected direc- 
tions. If you are familiar with track- 
ing experiments, do not be too quick 
to decide what this is all about. 

Equipment Required 

The basic equipment needed to do 
this experiment is: 

• A joystick with 1 degree of 
freedom (ie: a potentiometer with 
a stick on the shaft will suffice). 

• A reasonably fast analog-to-digital 
(A/D) converter with 7-bit or 
more accuracy. My system uses 
the Cromemco D + 7A, which has 
7 analog channels in and 7 out, as 
well as 1 input and 1 output 8-bit 
port. 

• A memory-mapped display, in 
which points are plotted on a video 
screen by depositing appropriate 
codes in a reserved segment of 
memory. This, or something 
equivalent, is essential for creating 
the moving objects that are involv- 
ed in the experiment. I use the 
Polymorphics VTI with the display 
area in the 1 K bytes of memory 
starting at hexadecimal location 
D000. Out of deference to systems 
that do not have the VTI's graphics 
capability (however crude), I have 
used 64 horizontal elements in the 
alphabetic mode. Higher resolu- 
tion would be much more desir- 
able, but this much is enough to 
show the principles well. 

If no memory-mapped display is 
available, but 2 digital-to-analog 
(D/A) outputs and a triggered 
oscilloscope are, the display that is 
needed can be created. Use 1 D/A 



96 Seplember 1979 © BYTE Publications Inc 



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7M89 
BYTE September 1979 97 



converter to deflect the trace in the Y 
direction, and the other (or 1 bit of a 
digital port) to trigger the sweep. By 
starting the sweep and then out- 
putting the 3 cursor values in se- 
quence, a 3-segment trace can be 
created, with the motion of the cur- 
sors being up-and-down instead of 
side-to-side, as in the following pro- 
gram. Lay the oscilloscope on its side 
if that deviation bothers you. 

Systems with built-in graphics 
under BASIC control, such as Apple, 
PET, or TRS-80, will probably allow 
the experiment to be done more 
simply than how I did it in listing 5. 
The basic requirement is to be able to 
read a number from a stored table, 
add the handle position to it, erase 
the old cursor, and use the sum to 
position the new cursor, doing this 
for 3 cursors at least 4 times per se- 
cond - the faster the better. (An exam- 
ple of the simulation on the Apple II 
is shown in listing 6.) 

Experimental Design 

Imagine a display with 3 cursors on 
it, one above the other. Each cursor 
can move left and right. The subject 
looks at this display while holding a 
control handle. The instructions for 
the first experiment are very simple: 
the subject is asked to select 1 of the 
cursors, and hold it still, somewhere 
near the center of the screen as ac- 
curately as possible for the duration 



North Star Strings 

The North Star BASIC string expression 
B$(I,J) corresponds to MID$ (B$,IJ) in other 
versions of BASIC. B$(I) corresponds to 
RICHT$(B$,I), and B$(1,I) corresponds to 
LEFT$(B$,1,I). 



of the run. Engineering psychologists 
call this "compensatory tracking." 
They use it to investigate the limits of 
speed and accuracy of control in the 
presence of rapid disturbances of 
various kinds. 

If the handle is held centered, each 
cursor will be seen to wander back 
and forth in a pattern that is indepen- 
dent of the other 2 cursors. In this ex- 
periment, the disturbances causing 
this wandering are made very slow 
and smooth. With even a slight 
amount of practice, every subject will 
be able to maintain essentially perfect 
control. Transfer functions will not 
be measured, nor will the limits of 
control be tested in the manner tradi- 
tional in engineering psychology. A 
subject acting well within the range of 
normal operations under conditions 
where the phenomena of control can 
be clearly seen is desired. The subject 
selects a visual variable (position of 1 
of the cursors), selects a reference 
level for that variable (a particular 
position), and maintains the perceiv- 
ed position at the reference position, 
while disturbances act that tend to 
move the cursor away from the 
reference position. 

Figure 17 shows the setup in 
schematic form. The 3 disturbances 
are labeled Dl, D2, and D3. The 3 
cursor positions are labeled Cl, C2, 
and C3. The position of the control 
handle is H. The position of each cur- 
sor is determined by the sum of H and 
one of the Ds. For cursor 2 the effect 
of the handle is reversed, so the 3 
relationships are: 



Cl 
C2 
C3 



Dl + H 
D2 - H 
D3 + H 



If the subject controls C3 in rela- 
tion to a reference position of (ie: 
midscreen), and does so perfectly, 
then = D3 + H, or H=-D3. The 
handle position should be an accurate 
mirror image of the magnitude of the 
disturbance D3 at every moment, and 
the cursor C3 does not move at all. 
You will find that all subjects, after a 
little practice, will closely approx- 
imate these predictions. 

This may seem elementary, ob- 
vious, boring and hardly worth the 
labor of getting the experiment up 
and running. Do not be deceived; this 
experiment appears to be simple 
because it is fundamental. It is fun- 
damental because it can prove that all 
of the life sciences have been using the 
wrong model. There are also several 
extensions of the experiment that will 
show how to get started mapping the 
whole hierarchy of human control 
systems. There is no theory and no 
simulation that carries the impact of 
seeing how a real living control 
system works; especially when you 
can understand every detail of what is 
happening, either as subject or 
observer. The 3 previous articles in 
this series have been designed to give 
the ability to grasp what is happening 
here. This experiment is designed to 
give the gut feeling of knowing. 

Program Structure 

The program in listing 5 is written 
in North Star BASIC, Version 6, 
Release 3. It contains a machine- 
language subroutine for an 8080/Z80 

Text continued on page 102 



Figure, table, and listing numbering continued 
from part 3. 



Z=RMD(A/100) 



Listing 5: North Star BASIC control-variable simulation. The necessary assembly language routines needed for execution are also 
given. 

10 DIM H$(16),D1$(250),D2$(250),D3$(250),H1$(250),F$<82),S$(82) 

20 DIM A$(2) 

30 H$="0123456789ABCDEF" 

40 INPUT "SEED FOR RANDOM GENERATOR (1 - 100) ",A\ 

50 REM ******************************* 

60 REM CONVERT 2 HEX DIGITS TO DECIMAL 

70 REM ******************************* 

80 DEF FNB(AS) 

90 U=ASC(A$(1,1))\IF U<58 THEN U=U-48 ELSE U=U-55 

100 V=ASC(A$(2,2))\IF V<58 THEN V=V-48 ELSE V=V-55 



110 
120 



RETURN 
FNEND 



16*U+V 



98 September 1979 © BYTE Publications Inc 



130 
140 
150 
160 
170 
180 
190 
200 
210 
220 
230 
240 
250 
260 
270 
280 
290 
300 
310 
320 
330 
340 
350 
360 
370 
380 
390 
400 
410 
420 
430 
440 
450 
460 
470 
480 
490 
500 
510 
520 
530 
540 
550 
560 
570 
580 
590 
600 
610 
620 
630 
640 
650 
660 
670 
680 
690 



REM 
REM 
REM 
INPUT 
GOSUB 
!"6 S 
M1 = 25 
DATA 
DATA 
DATA 
DATA 
M = M1 
READ 
FILL 
REM 
REM 
REM 
FILL 
FILL 
FILL 
FILL 
REM 
REM 
REM 
INPUT 
GOSUB 
FILL 
FILL 
REM 
REM 
REM 
W = 3*3 
\! 
"T 
"T 
\P 
"F 



*********************************** 

SET MACHINE-LANGUAGE PROGRAM ORIGIN 
*********************************** 

"MOST SIG. BYTE, SUBROUTINE LOCATION: ",SS 

1130 
EC TO LOAD SUBROUTINE" 
6*A0\ M2=Ml+9 

" 02 00000000000000004BDB 19071 F1 F4 73A0800FE00C21 C00782F" 
"3C477881E63F4F2A00003A08003C3CFE0 6DA2F00AF" 
"320800856F5E23563EA0127BE6C0B15F3EAA12722B73DB19EE80" 
"6F2600C9" 



!\ 

!\ 

!\ 

!\ 

!\ 

! \ 

N1=32 

FOR J 

D1SCJ 

D3$(J 

NEXT 

i » 

N3^25 
IF J- 
R1 = R1 
NEXT 
INPUT 
FOR J 
REM 
REM 
REM 
! \! \! 
GOTO 
FOR I 
FILL 



B$\FOR 

M,A\ M 

***** 

INSER 
***** 

M1+1,A 
M1+FNB 
M1+FNB 
M1+FNB 
***** 

SET L 
***** 

"MOST 

1130 

M1+2,F 

M1+6,F 

***** 

LOAD 
***** 

.14159 
A!\!\ 

HE SCR 
HEN TH 
ICK ON 
OR THE 

\ N2=3 
= 1 TO 
,J)=CH 
,J)=CH 
J 

CLOA 
\FOR J 
N3*INT 
+CRO-R 
J 

"READY 
= 1 TO 
***** 

EXPER 
***** 

\GOSUB 
690 
= 1 TO 

M 1+8,4 



J = 1 TO LEN(B$)-1 STEP 2\ A= FNB (BS ( J , J + 1 ) ) 
= M + 1\NEXT J\ IF AO201 THEN 250 
****************** 

T RELOCATION BYTES 
****************** 

0\ FILL M1+FNB("12"),A0 

("17"),A0\ FILL M1+FNB("23"),A0 

("2D"),A0 

("26"),A0\ FILL M1+FNB("31"),A0 

******************** 

OCATIONS FOR DISPLAY 
******************** 

SIG. BYTE, DISPLAY LOCATION: ",S$ 

NB("CO")\ FILL M1+3,A0\ FILL M1+5,A0+2 
NB("40")\ FILL M1+7,A0+3 
****************** 

DISTURBANCE TABLES 
****************** 

27/250\R0=RND(0)\Rl=32*R2=Rl 

CONE MINUTE TO LOAD DISTURBANCE 

EEN WILL CLEAR AND THREE 

REE CURSORS WILL APPEAR, 

E CURSOR AND TRY TO HOLD 

DURATION OF THE RUN, AS 

CSTAND BY FOR PROMPT]" 
1\ N3=25\ N4=64\ N5=10 
250 

R$(N1+N2*SIN(W*J) ) 
R$(64-ABS(J-125)/2) 

DING RANDOM DISTURBANCE: STAND BY]" 

=1 TO 250 

(J/N3)=Q THEN R0=N4*RND(0) 

1)/N5\ R2=R2+(R1-R2)/N5\ D2$ ( J , J ) =C HR$ CR2 ) 

TO GO: HIT RETURN TO PROCEED. ",A$ 
16\! \NEXT 
*********** 

IMENTAL RUN 
*********** 

680\! \!\!\!AGOSUE 680\ ! \ ! \ ! \ ! \GOSUP 6R0\!\! 

8\! "TTTTTTT+",\NEXT I\ RETURN 

\ REM SYNCH CURSOR COUNTER 



tables:" 
scales will appear." 
one for each scale." 
it in one position" 
exactly as you can." 



Listing 5 continued on next page 



September 1979 © BYTE Publications Inc 99 



700 N1=8\N2=127\N3=128\ FOR J=1 TO 250 

710 FOR L=1 TO 4 

720 OUT 25,N2\ OUT 26, N3 

730 H=CALL(M2,ASC(D1$(J,J))) 

740 H=CALL(M2,ASC(D2S(J,J))) 

750 H=CALL(M2,ASC(D3$(J,J))) 

760 NEXT L 

770 H1$(J / J)=CHR$(H) 

780 NEXT J 

790 REM ********************* 

800 REM DATA PLOTTING PROGRAM 

810 REM ********************* 

820 GOSUB 1050\ IF Y0<1 THEN 560 

830 !"AFTER PLOT, HIT RETURN TO CONTINUE" 

840 INPUT"WHICH CURSOR (1,2,3)? ",I 

850 IF 1=0 THEN 560 

860 FOR W=1 TO 250 STEP INT (250/ CYO+1 ) ) 

870 H=(ASC(H1$(W,W))-128)*X0/128 

880 ON I GOTO 890,900,910 

890 V=ASC(D1$(W,W) )-32\ GOTO 920 

900 V=ASC(D2$(W,W))-32\ H=-H\ GOTO 920 

910 V=ASC(D3$(W,W))-32 

920 V=V*X0/64+1 

930 C=V+H+ZO\ IF C<1 THEN C=1\ IF OXO THEN C=XO 

940 V=V+ZO\IF V<1 THEN V=1\ IF V>XO THEN V=XO 

950 H=H+ZO\ IF H<1 THEN H=1\ IF H>XO THEN H=XO 

960 B$=S$\B$(ZO,ZO)="." 

970 !#TO,\B£(V,V)="D"\ B$(H,H)="H"\ B$(C,C)="C" 

980 U=0\ IF V>U THEN U=V\IF H>U THEN U=H\IF OU THEN U=C 

990 IF ZO>U THEN U=ZO\B$=B$ (1 ,U) \ !#TO,P$, 

1000 NEXT W 

1010 INPUT1"",A$\ GOTO 820 

1020 REM ******************************** 

1030 REM SET UP FOR PLOTTING (SUBROUTINE) 

1040 REM ******************************** 

1050 !\INPUT "Y-DIMEflSION OF PLOT (0 = NEW RUN): ",Y0\ Y0 = Y0-2 

1060 IF Y0<1 THEN RETURN 

1070 INPUT "X-DIMENSION OF PLOT (1-72): ",X0 

1080 IF X0>72 THEN 1070\ IF X0<1 THEN 1070\X0=X0-2 

1090 INPUT "OUTPUT DEVICE (T OR S)",A$ 

1100 IF A$="T" THEN T0=2 ELSE T0=0 

1110 SS = ,,M \FOR 1 = 1 TO XO\S$ = S$ + " "\ NEXT I 

1120 Z0=INT(X0/2)\ RETURN 

1130 REM ********************************** 

1140 REM CONVERT HEX IN S$ TO DECIMAL IN AO 

1150 REM ********************************** 

1160 A0=0\K = 1\F0R J = 1 TO LEN (S$ )-1 \K = K*1 6\MEXT J \K = INT (K + . 01 ) 

1170 FOR I = 1 TO LEN(S$) 

1180 FOR J=1 TO 16 

1190 IF S$(I,I)=H$(J,J) THEN EXIT 1220 

1200 NEXT J 

1210 !"NOT HEX NUMBER"\ EXIT 160 

1220 AO = AO + K*(J-1)\ K=K/16 

1230 NEXT I 

1240 RETURN 

1250 REM ******************************* 

1260 REM UTILITY, CONVERT HEX TO DECIMAL 

1270 REM UP TO TEN HEXADECIMAL DIGITS 

1280 REM DO "RUN 1300" 

100 September 1979 © BYTE Publications Inc 



1290 REM ******************************* 

1300 DIM HS(16)\H$="0123456789ABCDEF"\! 

1310 INPUT1"HEX= ",S$\G0SUB 1160\!" DECIflAL= ",A0\GOTO 1310 



001 






* 


MACHINE LANGUAGE 


002 






* 






003 








ORG 





004 






* 






005 


0000 


0200 


ADRO 


DBL 


ADR1 


006 


0002 


0000 


ADR1 


DBL 





007 


0004 


0000 


ADR2 


DBL 





008 


0006 


0000 


ADR3 


DBL 





009 


0008 


00 


COUNT 


DATA 





010 


0009 


4B 


START 


MOV 


C,E 


011 


OOOA 


DB19 




IN 


25 


012 


OOOC 


071F1F 




ARS 




013 


OOOF 


47 




MOV 


B,A 


014 


0010 


3A0800 




LDA 


COUNT 


015 


0013 


FE02 




CPI 


2 


016 


0015 


C21C00 




JNE 


S1 


017 


0018 


78 




MOV 


A,B 


018 


0019 


2F 




CMA 




019 


001A 


3C 




INR 


A 


020 


001B 


47 




MOV 


B,A 


021 


001C 


78 


S1 


MOV 


A,B 


022 


001D 


81 




ADD 


C 


023 


001E 


E63F 




ANI 


:3F 


024 


0020 


4F 




MOV 


C,A 


025 


0021 


2A0000 




LHLD 


ADRO 


026 


0024 


3A0800 




LDA 


COUNT 


027 


0027 


3C 




INR 


A 


028 


0028 


3C 




INR 


A 


029 


0029 


FE06 




CPI 


6 


030 


002B 


DA2F00 




JLS 


S2 


031 


002E 


AF 




ZAR 




032 


002F 


320800 


S2 


STA 


COUNT 


033 


0032 


85 




ADD 


L 


034 


0033 


6F 




MOV 


L,A 


035 


0034 


5E 




MOV 


E # M 


036 


0035 


23 




INX 


H 


037 


0036 


56 




MOV 


D / M 


038 


0037 


3EA0 




MVI 


A,:AO 


039 


0039 


12 




STAX 


D 


040 


003A 


7B 




MOV 


A,E 


041 


003B 


E6C0 




ANI 


:C0 


042 


003D 


B1 




ORA 


C 


043 


003E 


5F 




MOV 


E,A 


044 


003F 


3EAA 




MVI 


A,:AA 


045 


0041 


12 




STAX 


D 


046 


0042 


72 




MOV 


M,D 


047 


0043 


2B 




DCX 


H 


048 


0044 


73 




MOV 


M,E 


049 


0045 


DB19 




IN 


25 


050 


0047 


EE80 




XRI 


:80 


051 


0049 


6F 




MOV 


L,A 


052 


004A 


2600 




MVI 


H,0 


053 


004C 


C9 




RET 





SUPPORT ROUTINES 



GET HANDLE 
DIVIDE BY TWO 
SAVE IN B 
CHECK FOR MIDDLE 



ONE 



IF MIDDLE ONE NEXT, 
MAKE HANDLE NEG. 
(TWO'S COMPL.) 



X=X+HANDLE 
LIMIT TO 63 
SAVE X IN C 
GET BASE ADDRESS 
GET DISPLACEMENT 

BUMP TWICE 

CHECK MODULO 6 



MAKE ADDRESS FOR 
CURRENT CURSOR. 



DE=OLD SCREEN ADR. 
LOAD A SPACE 
ERASE OLD CURSOR 

ZERO DISPLACEMENT 

NEW DISPLACEMENT 

POINTER FIXED 

LOAD ASTERISK CURSOR 

PUT IT ON SCREEN 

SAVE CURSOR 

ADDRESS 

GET HANDLE AGAIN 
RANGE 0-255 



September 1979 © BYTE Publications Inc 101 



5 


HIMEM: 8192 


10 


DIM D1 %(250),D2%(250),D3%(250),H1 %(250) 


20 


INPUT "SEED (0-100): ";A 


30 


Z = RND(A/ 100) 


40 


REM LOAD DISTURBANCE TABLES 


50 


W = 3 . 3.141592654 / 250 


60 


R0 = RND(0):R1 = R2 = 140 


65 


PRINT : PRINT : PRINT : PRINT : PRINT : PRINT : PRINT : PRINT 


70 


PRINT : PRINT : PRINT "LOADING DISTURBANCE TABLES" 


75 


PRINT 


80 


PRINT "WHEN SCREEN CLEARS, BACKROUND WILL" 


85 


PRINT 


90 


PRINT "APPEAR — THEN THREE CURSORS." 


95 


PRINT 


100 


PRINT "PICK ONE CURSOR AND HOLD IT IN" 


105 


PRINT 


110 


PRINT "ONE POSITION FOR THE DURATION OF" 


115 


PRINT 


120 


PRINT "RUN, AS ACCURATELY AS YOU CAN- 


125 


PRINT 


130 


PRINT "STAND BY FOR PROMPT MESSAGE" 


140 


FOR J = 1 TO 250 


150 


D1%(J) = 140 + 130 * SIN (W , J) 


160 


D3%(J) = (125 - ABS (J • 125)) . 270 / 125 


170 


NEXT J 


175 


PRINT 


180 


PRINT "RANDOM DISTURBANCE LOADING: STAND BYE." 


185 


N3 = 25:R1 = 140:R2 = 140 


190 


FOR J = 1 TO 250 


200 


N3 = N3- 1: IF N3 > THEN 210 


205 


N3 = 25:R0 = 280 . RND (5) 


210 


R1 = R1 + (R0 ■ R1) / 05:R2 = R2 + (R1 - R2) / 5 


220 


D2%(J) = R2 


230 


NEXT J 


240 


PRINT : INPUT "HIT RETURN FOR RUN";A$ 


250 


HGR 


255 


HCOLOR= 3 


260 


POKE 49234, 


261 


FORX = 1 TO 280 STEP 10 


262 


FOR Y = 43 to 143 STEP 50 


263 


HPLOTX.Y: HPLOT X,Y 4- 14 


264 


NEXT Y: NEXT X 


270 


FOR J = 1 TO 250 


280 


FOR K = 1 TO 4 


290 


H = PDL(0)- 128 


299 


HCOLOR = 0: HPLOT C1 % , 45 TO C1 % ,55: HCOLOR = 3 


300 


C1% = D1%(J) + H 


305 


IF C1% < 0THEN C1% = 


306 


IF C1 % > 279 THEN C1 % = 279 


307 


HPLOT C1 %,45 TO C1 %,55 


309 


HCOLOR= 0: HPLOT C2%,95 TO C2%,105: HCOLOR= 3 


310 


C2% = D2%(J)- H 


315 


IF C2% < 0THEN C2% = 


316 


IF C2% > 279 THEN C2% = 279 


317 


HPLOT C2%,95 TO C2%,105 


319 


HCOLOR = 0: HPLOT C3%, 145 TO C33%, 155: HCOLOR = 3 


320 


C3% = D3%(J) + H 


325 


IFC3% < 0THENC% = 


326 


IFC3% > 279 THEN C3% = 279 


327 


H PLOT C3 % , 1 45 TO C3 % , 1 55 


370 


NEXTK 


380 


H1%(J) = H 


390 


NEXT J 


400 


HGR 


405 


POKE 49234, 


410 


FOR J = 1 TO 250 


420 


Y = 191 - J * 191 /250 


430 


U = 88 / 280 


435 


H = INT (H1 %(J) , U) 


440 


D1 = INT((D1%(J)- 140) . U + 45) 


450 


D2 = INT (D2% J) - 140) * U + 135) 


460 


D3 = INT((D3%(J) - 140) . U + 225) 


461 


C1 = D1 + H:C2 = D2 - H:C3 = D3 + H 


462 


IFC1 < 0THEN C1 = 


463 


IF C3 > 278 THEN C3 = 278 


480 


HCOLOR = 1 


490 


HPLOT D1,Y: HPLOT D2,Y: HPLOT D3,Y 


500 


HCOLOR = 2 


510 


HPLOT C1 ,Y: HPLOT C2,Y: HPLOT C3,Y 


520 


HCOLOR = 3 


530 


HPLOT H + 45, Y: HPLOT ■ H + 135, Y: HPLOT H +225.Y 


540 


NEXT J 


550 


INPUT "";A$ 


560 


TEXT 


570 


GOTO 180 



Listing 6: A computer such as the Apple II 
which has high-resolution graphics capa- 
bilities greatly simplifies the program 
originally given in listing 5. This program 
performs the same operations as the simu- 
lation in listing 5. The author acknow- 
ledges the assistance of Charles Faso from 
Computerland of Niles IL in preparing 
this program. 

Text continued from page 98: 

processor which is loaded by the 
BASIC program at any specified 
256-byte memory-address boundary 
(specify in hexadecimal only the 
most significant byte of the location 
of the subroutine). 

The machine-language subroutine 
reads in the handle position, adds it 
with the appropriate sign to the value 
of a disturbance that is passed to the 
subroutine by the CALL command 
(in the DE register pair), erases the 
old cursor, and deposits the new cur- 
sor, a rubout, on the screen. Each 
time the subroutine is called it steps to 
the next cursor, recycling as 
necessary. On return from the 
subroutine, the handle position is 
passed back to the main program (in 
the HL registers). The machine- 
language program is in lines 200 thru 
230, expressed as a string of hex- 
adecimal bytes with no punctuation. 
Thus if your machine is not an 
8080/Z80 type, a program can be 
assembled, the listing copied into 
these lines, and possibly this program 
can be made to work with little other 
modification. 

The program asks for the most 
significant byte of the place where the 
machine-language subroutine is 
stored. The loader adjusts memory 
references by inserting the value of 
this byte in memory wherever 
necessary, after the program is loaded 
(lines 300 thru 330). 

The display area consists of 1 K 
bytes of memory starting on any 
256-byte boundary. Lines 370 thru 
400 ask for the starting location of the 
memory area devoted to the display, 
and set up base registers in the 
machine-language program for the 
left margin of each cursor's move- 
ment. The FILL command is like 
POKE. If the computer has graphics 
capability built-in, everything from 
line 60 thru 400, and the plotting 
subroutine (later), can be accomplish- 
ed in a simpler way. 

Disturbance tables are set up in 
lines 510 thru 620. The unnecessary 
use of symbols, instead of constants, 



102 September 1979 © BYTE Publications Inc 



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HANDLE 




Figure 17: Schematic arrangement of experimental setup. Three slow and smooth distur- 
bances are added to a measure of the handle position (with a negative sign for the 
middle one), to determine the position of 3 corresponding cursors. The subject selects 1 
cursor and a reference position for it, and uses the handle to maintain the cursor at that 
position. A run lasts about 1 minute, and 250 samples of handle position are recorded. 
For plotting, the cursors are reconstructed from the tables of disturbances and the 
corresponding records of handle position. 



is an attempt at acceleration. It still 
takes a minute to load the 3 distur- 
bance tables, each 250 bytes long. All 
long tables are strings; only 8 bits of 
accuracy is needed, so by using the 
CHR$ and ASC functions, the tables 
can be stored 1 byte per value instead 
of 5 bytes per value. Disturbances are 
in tables because BASIC cannot 
calculate them fast enough. 

Disturbance Dl is a sine wave and 
D3 is a triangular wave. D2 is a 
smoothed random disturbance. On 
reruns, only D2 is reloaded, taking 
about 20 seconds. 

The experimental run is controlled 
by lines 660 thru 780. Lines 660 and 
680 lay down 3 arbitrary scales on the 
screen, while the rest repeatedly call 
the machine-language subroutine. For 
each stored value of each distur- 
bance, all 3 cursor positions are com- 
puted and plotted, and the handle 
position is stored in the table Hl$. 
The inner loop from line 710 to line 
770 adjusts the duration of the ex- 
perimental run; here it is set up so 
that the disturbances change and a 
handle position is recorded only 
every fourth time the display is 
generated. On my system, this works 
out so the display is refreshed 16 
times per second, and data is sampled 
and stored 4 times per second. The 2 
OUT statements reflect my laziness; I 
use 2 digital-to-analog outputs to 
supply the voltage to the poten- 
tiometer that measures handle posi- 
tion. 

The data plotting routine (lines 820 
thru 1010) is entered at the end of an 
experimental run. This routine is set 
up to plot either on the video screen 



or on a hard-copy device; it asks for 
the X and Y dimensions of the plot, 
which cursor is to be plotted, and 
which device is to be used. My system 
is set up so the typewriter is device 2 
and the screen is any other device 
number. If you do not have this 
ability in your BASIC or system, 
delete lines 1060 and 1070 (in the 
subroutine that requests information 
about the display), and eliminate the 
"#2," in lines 970 and 990. In North 
Star BASIC, the exclamation point is 
short for PRINT. 

Only the handle position is stored 
as data; the cursor positions are 
reconstructed during plotting from 
the list of handle positions and the 
corresponding tables of disturbances. 

The plotting scheme is designed to 
work with any teletypewriter-like 
device. If you have legitimate 
graphics, you can rewrite this part 
and get a more pleasing result. 

There are 3 choices for plotting, 
each associated with cursors Cl, C2, 
and C3. Each plot shows the cursor as 
a C, the handle position as an H, and 
the disturbance acting on the cursor 
as a D. A dot indicates the center of 
the display when nothing else is there. 
After each plot is finished, there is a 
pause; hitting the carriage return will 
cause the program to ask about the 
next plot. If the question about the Y 
dimension of the display is responded 
to with a 0, the program will reload 
the random disturbance table and 
issue a prompt for another ex- 
perimental run. The old data will be 
destroyed. Remember, it takes about 
20 seconds to reload the random 
disturbance table. Do not panic if 



104 



September 1979 © BYTE Publications Inc 




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BYTE September 1979 105 



there is a long pause. 

At line 1260 there is a utility 
routine that converts any hex- 
adecimal number up to 10 digits to a 
decimal number. I used it while 
writing the program. It calls the con- 
version subroutine starting at line 
1130. 

Running the Experiments 

If you possibly can, take the 
trouble to set this experiment up. 
Nothing can take the place of actually 
experiencing yourself as a control 
system and understanding things that 
you have taken for granted all your 
life. 

Here is a typical run for the benefit 
of the many readers who do not have 
the equipment to do this; the data will 
then be observed. Here is an old 
friend, Chip Chad (from part 1 of this 
series), glaring at the screen and 
maintaining a choke-hold on the 
handle, waiting for the experimenter 
to hit the return key at line 610. The 
experimenter reaches in and taps the 
key. The reference scales slide up into 
place and the 3 cursors pop into view, 
moving. Chip picks the middle one as 
most people do the first time, decides 
to keep it on the middle + mark, and 
after a few wobbles succeeds. 

'So what?" he says. 

If learning were being studied, 
good information could be obtained 
from this first run. But the plan is to 
see Chip acting as a competent con- 
trol system, so his first effort is 
praised and he is given another run 
(answering the query about Y dimen- 
sion with a 0). After the second run, 
the data is plotted for each cursor. 

Figure 18 shows the data for each 
cursor, number 1 on the left, 2 in the 
middle, and 3 on the right. The 2 end 
plots are a mess, but the middle plot 
shows a striking symmetry. The Cs 
march more or less down the center 
of the screen, deviating a little to left 
and right, but maintaining a constant 
position on the average. The Ds make 
a random-looking pattern, and the Hs 
follow almost the mirror image of the 
D pattern. 

Looking carefully at the middle 
plot, could it be said that the handle 
position or motion looks like any sort 
of regular function of the cursor posi- 
tion or motion? There may be some 
relationship, but it certainly is not 
clear. Probably, nobody would claim 
that the large, smooth motions of the 
handle could be reconstructed ac- 



curately on the basis of measurements 
of cursor position (that is, recon- 
structed roughly or statistically with 
accuracy, especially if handle ac- 
celeration is compared with cursor 
deviation from the average position). 
The best which could be hoped for 
would be some statistical relationship 
(eg: a small signal buried in much 
noise). 

On the other hand, the relationship 
between the handle position and the 
magnitude of the invisible distur- 
bance is obvious and quantitative. It 
is seen that the handle position is the 
mirror image of the disturbance 
magnitude with an error of only a few 
percent of full scale. There is much 



signal and little noise in that relation- 
ship. 

Here is the situation. There is 1 
measure of Chip's behavior, H. There 
are 2 variables, D and C, either of 
which might have some relationship 
to that behavior. Which variable, D 
or C, would be selected by any 
statistical test as the most probable 
cause of the behavior? Of course, D 
would be selected. In fact, a formal 
statistical analysis, like those done in 
every scientific study of behavior, 
shows D to be the only significant 
contributor to the behavior, while C, 
the cursor position, is rejected as an 
irrelevant variable! 

That is a paradox, however, from 



Figure 18: A typical run for a practiced subject. In figure 18a is the record for Dl, Cl, 
and H. Figure 18b has the record for D2, C2, and H; figure 18c has the record for D3, 
C3, and H. In figure 18b, the cursor is held near the center, while the handle position is 
at all times very nearly the mirror image of the disturbance amplitude. It is very easy to 
decide which cursor was under control. 




D 

C H 







H 


C 




H 




C 


H 






C 


H 


D 


c 


H 




D 


c 


H 






D C 


H 






DC 
DC 


H 






DC 


H 






D C 


H 




D 


C 




H 


D 


C 


D 




H 


C 






H 


C 






H 


C 



H C 



D C 

D C 

DC 

DC 

D C 

D C 

C 



106 



September 1979 © BYTE Publications Inc 



Figure 19: Cause and effect paradox. Under the old concept that stimuli cause behavior, 
the cause and effect chain runs from the disturbance to the cursor, through the subject, 
to the behavior. However, the correlation of the disturbance and the cursor position is 
very low, as is the correlation of the cursor position and handle position (for the con- 
trolled cursor). This would lead to a prediction of an even lower correlation of distur- 
bance and behavior. In fact, that correlation is normally very high (0.99 or better). 
Only the control theory analysis of this experiment can explain this otherwise paradox- 
ical situation. 



CORRELATION > 0.99 



— c- 



SUBJECT 



CORRELATION < 0. 



CORRELATION < 0.1 



the traditional point of view. The 
only way D can affect Chip's 
behavior is through its effects on C, 
since all that Chip can sense is the 
cursor position. The disturbance itself 
is invisible. If C does not correlate 
with the behavior, then how can 
anything that acts exclusively 
through effects on C correlate any 
better with behavior? Yet a typical 
correlation between C and H is 
around 0.1, while the correlation of H 
with the corresponding D is typically 
0.995. See figure 19. 



That is the proof mentioned earlier. 
The old cause-effect model fails 
utterly when applied to this situation. 
The question then is, why have 
generations of intelligent people 
believed that behavior is caused by 
sensory stimulation? The answer is 
clear: they have been fooled by a 
monstrous illusion. 

The illusion would be easier to see 
if there was some visible, direct in- 
dication of the magnitude of the 
disturbance. Suppose there were a 
moving D (or a number that con- 



tinually reflected the magnitude of D) 
on the display. Clearly, if Chip 
managed to control C without that 
indication, he could still do so; he 
could ignore it and perform as well as 
ever. However, something has now 
been added that would mislead a 
bystander who did not understand 
control theory. 

That bystander could now see 2 
variables, both able to affect Chip's 
senses. Taking the apparent relation- 
ships at face value, it would be clear 
that the indication of D was accur- 



(18b) 



„H 
C . 
C. 
i C. D 

H .C D 

H C. D 

H C. D 

H C. D 

H .C D 

H C. D 

H C. D 

i C D 

C 

c 
c. 
c. 

C D 

H CD 

H CD 

D C. H 

D C H 

D C H 

D C. H 

D C. H 

D CH 

CH 

C. H 

D C . H 

D C H 

D C H 

D C. H 

) C K 

C. 

c. 
c 
c 

) C. H 

D C H 

D C H 

H C D 

H C D 

H .C D 

H C. D 

H C. D 

H C D 

H C. D 

HCD 

D C. H 

D C H 

D C H 



DC 



(18c) CD H 

D C. 

D C 

D C 

D C 

D C, 

D 
D 
D 
D 
D 
D 



H 
H 
H C 

H C 

H C 

H C 

H C 

H C 

HC 

HC i 
DC 
D 
D C 

D C 

D C 

D C 

D C 

DC I 

CD H 

CD H 

CD H 



H 
H 
C H 

C H 

C H 

C H 

C H 
CH 
D HC 

D H C 

D H C 

D H C 

D H C 

H D C 

H DC 

C D 
C D 

C D 

C D 

C D 
C D 
C 
C D 
C D 

C D 

C D 

C D 

D 
D 
D 
D 
D 
D 
D 

H 

C H 

H 
H 
H 
H 
H 



September 1979 © BYTE Publications Inc 107 



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ately associated with the handle posi- 
tion; while the movements of the cur- 
sor, such as they are, show no such 
association. Furthermore, the varia- 
tions of D are large and smooth, and 
there is no observable relationship 
between D and C. Why should the 
bystander suspect that C is being 
affected by D in one way and affected 
by H in an opposite way? The ob- 
vious conclusion is that the variations 
in D are causing Chip's behavior, 
while C has nothing to do with his 
behavior, especially if C does not 
vary more than the fixed background 
scales do. If the screen were full of 
irrelevant cursors, jiggling around 
slightly, how could the bystander 
pick C as something of special impor- 
tance? If BASIC were fast enough, I 
would have included such irrelevant 
cursors; the point being made here 
would then be obvious. 

An organism is surrounded by a 
world full of variables; variables that 
change within widely diverse ranges. 
The organism receives many signals 
from its internal parts, too. In that 
sort of situation, if the organism is 
controlling some of the variables, it 
will react strongly and smoothly to 



any disturbance tending to alter 1 of 
the controlled variables. The result is 
that it will seem to be responding 
directly to the disturbances. There 
will be no obvious indication that it is 
controlling anything at all. There is 
every excuse for even the best of 
scientists to have observed the rela- 
tionship between disturbance and 
behavior, and to have missed the 
very existence of controlled variables. 

The name for such disturbances is 
stimuli. Once in a while, an ex- 
perimenter must have accidentally 
picked a real controlled variable to 
call a stimulus, but the chances are 
against that. If an attempt is made to 
manipulate a real controlled variable, 
the organism will have to be strapped 
down to keep it from interfering. 
That is what is done in such cases. If 
the organism insists on acting like a 
control system, forcibly break the 
loop and make the organism conform 
to the theory. As a famous 
psychologist said, the theme is 
"Behave, damn it!" It never occurs to 
such stong-willed individuals that 
they might have the wrong idea about 
what is happening. 

There is more in this elementary ex- 



periment than meets the eye. If all 
psychologists were to experience it, 
and try to meet the challenge of ex- 
plaining these effects using any stan- 
dard theory, the result would be a 
total collapse of that science, follow- 
ed by a rebirth. However, many jobs 
would be threatened. What has 
happened instead is that a handful of 
psychologists has supported this 
theory, another handful has taken up 
arms against it, and most have 
resolutely ignored it. 

I suggest that you run this experi- 
ment many times with subjects con- 
trolling all 3 cursors. Every case will 
show that mirror-image relationship 
between D and H and little relation- 
ship between C and either D or H. If 
the previous parts of this series are 
studied and all the relationships that 
make up a control system thought 
about carefully, it will be evident that 
there is no other explanation for what 
is going on here. If you get nothing 
else out of this, you should acquire an 
intuitive feel for a new theory of how 
behavior works. You might even 
begin to understand how to design a 
robot in a new way. 

It is time now to try to fulfill a pro- 



108 September 1979 © BYTE Publical 



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mise implied in part 1, to show how 
anyone with a home computing 
system can make important contribu- 
tions to this new science of human 
nature. The best way this can be done 
is to start with the experiment used, 
and to show how it can be extended 
to become a powerful tool for in- 
vestigating human organization. The 
main objective will be to introduce 
the test for the controlled variable, 
the nearest approach I know of to 
mind reading. 

More Controlled Variables 

Once subjects controlling all 3 cur- 
sors have been seen, it might seem 
that the possibilities of this experi- 
ment have been exhausted; this is not 
the case at all. There are controllable 
variables all over that screen; all of 
them can be controlled by the same 
means, movements of the handle in 1 
dimension. Discovering them is a 
good way to get out of the habit of 
thinking that we simply perceive our 
environment, and start a new way of 
thinking: to recognize that we con- 
struct perceptions, imposing order on 
our experiences far more than 
recognizing order. As you will see, a 



controlled variable does not have to 
be "real" at all. 

Here is an example. It is possible to 
perceive the relative position of any 
of the 2 cursors. The handle affects 
C2 in a direction opposite to its 
effects on Cl and C3, so the relative 
position of Cl and C3 cannot be con- 
trolled because the handle does not 
affect it. However, it is possible to 
keep Cl even with C2, or C2 even 
with C3; in fact, it is easy. A plot of 
the results would involve plotting 
C2-C1 or C3-C2 instead of just C, 
and D2-D1 or D3-D2 instead of just 1 
disturbance. The mirror image rela- 
tionship with H would be as good as 
ever. Do not forget that C2-C1 and 
C3-C2 are variables. Any value of the 
variables can be selected as a 
reference level (eg: Cl to be 1 inch to 
the left of C2). 

These are examples of higher-level 
controlled variables. If the subject 
could not perceive the present posi- 
tions of the cursors, he or she cer- 
tainly could not perceive their 
relative positions. Relative position is 
derived from perceptions of in- 
dividual positions, but not vice versa. 
In order to control relative positions, 



it is necessary to control (or at least 
vary) individual positions, but in- 
dividual positions can be controlled 
without controlling relative posi- 
tions. These are the relationships one 
looks for to map out a hierarchy of 
perception and control. 

Other relative perceptions can be 
controlled. All 3 cursors can be kept 
lying in a straight line, at least within 
the range where 1 of them does not 
fall off the edge of the display and 
pop up at the other edge. Reducing 
the amplitude of the disturbances 
would eliminate that problem. Also, 
the 3 cursors can be made to form any 
fixed angle, subject to the same 
limitation. There may be more static 
patterns that can be controlled, but I 
have not thought of any. This is, after 
all, a simple display. 

It is not, however, limited to static 
conditions. Suppose the subject 
visualizes a pattern in which 1 cursor 
moves back and forth slowly between 
2 limits. This pattern can easily be 
maintained, the handle moving just 
enough to produce it, and enough 
more to cancel the effects of any of 
the disturbances. A similar oscillation 
could be maintained for the relative 



September 1979 © BYTE Publications Inc 109 



variables. This is a still higher-level 
variable, a temporal pattern. The 
subject chooses which temporal 
pattern to perceive, and what state of 
that kind of pattern to maintain. 
Control still requires only the use of 
the 1-dimensional effect caused by the 
handle. 

There is clearly an infinite range of 
different temporal patterns, ranging 
from a simple steady motion in 1 
direction to completely arbitrary mo- 
tions and rhythms. There is an 
unlimited number of potential con- 
trolled variables in this simple 
display. Anything that can be 
perceived, and that the handle can 
affect in a systematic way, can be 
controlled. 

For all of these examples of con- 
trollable perceptions, it is essential to 
remember that the disturbances are 
acting all the time. This is not a 
matter of producing any particular 
behavior. The cursor cannot be made 
to move slowly back and forth be- 
tween fixed limits just by moving the 
handle slowly back and forth be- 
tween fixed limits. The handle might 
be moving the wrong way at many 



moments, when the disturbance tends 
to make the cursor move faster than 
the reference pattern being con- 
sidered. There is no one-to-one cor- 
respondence between handle position 
or velocity and cursor position and 
velocity, because of those ever- 
present disturbances. Regularities of 
behavior are not being looked at 
here, but regularities of controlled 
perceptions. If there were a slowly 
oscillating prism between the display 
and the subject's eyes, a regular pat- 
tern of movement of the cursor on the 
screen would not be seen. The subject 
controls the visual image, not the 
reality. For the higher-level variables, 
the subject controls some function of 
the visual image (often the controlled 
variable could not be found, even on 
the retinas). 

One could create displays of far 
greater complexity, and provide 
means of affecting the display that 
have more than 1 degree of freedom 
to explore a staggering range of possi- 
ble controlled variables. This is what 
I suggest be done. The first step in the 
development of any new science is ac- 
quire the facts; here the most needed 



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facts concern what variables human 
beings can actually control. What is 
needed is a large and simpleminded 
program of recording the obvious 
and obscure. What is needed is a 
body of definitions of variables in 
every sensory mode that people have 
been able to control. Order and 
system count much less than sheer 
volume of data at this point. In fact, 
an unsystematic gathering of data 
may be the best kind, since it will not 
be constrained by theories about 
what people ought to be able to con- 
trol. Anything which can be a way of 
testing is worth testing at this stage. 
The possibilities are limited only by 
the imagination. 

We do need some sort of ordering 
principle — some criterion for judging 
the reality of any proposed controlled 
variable. This is where the test ap- 
pears; here is how it works. 

Test for Controlled Variables 

The first thing to remember when 
investigating a possible controlled 
variable is that in order for something 
to be controllable it has to be 
variable. There is neither the means 
nor the need to control the existence 
of the Empire State Building or the 
planet Jupiter. Not all perceptions are 
controlled. Some are just distur- 
bances; some are just there. 

One might think initially about 
controlling, for instance, a car. 
People often speak casually about 
controlling things. But what is meant 
is controlling something about those 
things. A person cannot really con- 
trol a car; but under proper cir- 
cumstances its shape, its color, its 
price, its speed, its direction, its park- 
ing place, its dirtiness, its 
dangerousness, its desirability, its 
altitude, or the flatness of its tires can 
be controlled. A car, after close in- 
spection, proves to be composed en- 
tirely of hundreds or even thousands 
of variables. Together they create 
"car-ness" in our perceptions. In- 
dividually, or in groups, most of 
them can be affected by one means or 
another, and can be controlled if it is 
worth the effort. You can even make 
the car disappear instantly by closing 
your eyes. Keep remembering that 
what is controlled is really a percep- 
tion. 

The first step in applying the test 
for the controlled variable is to define 
a variable. You do not have to know 
in advance if it is a controlled 



110 Seplember 1979 © BYTE Publications Inc 



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variable; you do not even have to 
know where the supposed control 
system is. All you have to do is to 
pick out something that you know is 
variable and "push" on it. 

By push I mean to apply a distur- 
bance that under normal cir- 
cumstances should have a predictable 
direction and amount of effect on the 
variable. If I push hard enough on a 
life-sized statue, it should tilt in the 
direction of the push. Perhaps it will 
topple in that direction according to 
the simple laws of mechanics. 

Having selected a variable and ap- 
plied a push to it, the next step is to 
measure the actual effect of the push. 
I predict that pushing on this statue 
should make it tilt a certain amount 
in a certain direction. I apply the push 
and observe the tilt. 

If the actual effect is far smaller 
than the predicted effect, common 
sense indicates that something must 
be pushing back. If the pushing-back 
is always just enough to cancel any 
amount or direction of disturbance 
(within some limits), it can be con- 
cluded that the pushing-back is 
systematic. The mirror-image effect 
that has been observed is what is 
wanted. 

It is necessary to discover what is 
pushing back, and how it is doing the 
pushing. Perhaps, examining the 
statue carefully, an iron rod is found 
supporting its back from its base. In 
that case, a conclusion is made that 
there were not enough facts to make a 
correct prediction of the effects of the 
push; the bending moment of the rod 
should have been taken into account. 
But if no simple explanation for the 
failure of the prediction is found, one 
must look further. 

Suppose it is discovered that the 
base of the statue seems to move 
when pushed. If there is a push to the 
east, the base tilts to the west moving 
the center of support east of the 
center of gravity of the statue, and 
thus creating a counterforce. Suppose 
this tilt of the base is found to be 
always just what is required to offset 
the effects of the push. It can be con- 
cluded that one may be on the trail of 
a control system. 

What has been done is to find out 
something about the means of con- 
trol, the path by which the output of 
the control system, if it exists, might 
be linked to the controlled variable 
(the angle between the statue's 
longitudinal centerline and the ver- 



tical). Finding this link is a necessary 
step in the test. 

That step will usually lead to 
discovering the physical control 
system. Tracing the wires that work 
the motors that tilt the base of the 
statue, you find a black box a few 
yards away from the statue. That 
may be the control system, or at least 
all of it that is not its actuators (which 
have been found). 

There is still one step to be taken. 
You cannot be completely sure of the 
nature of the control system until you 
discover the variable it is really 
sensing. The situation has been 
approached with human prejudices; 
to me, it seems that the controlled 
variable is the orientation of the 
statue, a geometric or visual variable. 
Perhaps that variable is only related 
to the real controlled variable. What 
must be found now are the sensors 
that the control system is using. 

Thinking in visual terms, you 
might look for a photocell that 
detects the tilt. Suppose a photocell is 
found on a stand near the statue. The 
test calls for breaking this link, 
preventing the sensing of the statue. 
The result should be that the effect of 
the push returns to what would be 
predicted from mechanical laws. So 
the photocell is covered and the 
disturbances are applied again. What 
happens is that the floodlights il- 
luminating the statue turn on. The 
statue still resists the push — the 
photocell was for something else. 

By careful searching 4 strain gauges 
built into the base of the statue are 
discovered. These provide a signal 
showing where the center of thrust is, 
and the wires from the strain gauges 
run over to that black box. Discon- 
necting the wires shows that now the 
push succeeds in tilting the statue. As 
soon as its tilt becomes marked, an 
angry groundskeeper comes leaping 
out of the bushes and arrests the ex- 
perimenter. Aha! You may have 
discovered another control system 
controlling the state of the statue. 

To recapitulate, the test for the 
controlled variable involves the 
following steps: 

1. Define a variable. 

2. Apply various amounts and 
directions of disturbances 
directly to the variable. 

3. Predict the expected effects of 
the disturbances, assuming no 
control system is acting. 



4. Measure the actual effect of the 
disturbances. 

5. If the actual effect is essentially 
the same as the predicted effect, 
stop. No control system is 
found. 

6. If the actual effect is markedly 
smaller than the predicted 
effect, look for the cause of the 
opposition to the disturbance, 
and determine that it results 
from systematic variations in 
some other variable. If such a 
cause is found, it may be 
associated with the output of a 
control system. 

7. Look for a means of sensing the 
controlled variable. If none is 
found, stop: no control system 
is proven to exist. 

8. If a means of sensing is found, 
block it, so the variable cannot 
be sensed. If control is not lost, 
the sensor is not the right one. If 
no such sensor is found, stop: 
no control system is proven to 
exist. 

9. If all steps of the test are passed, 
the variable is a controlled 
variable, its state is its reference 
level, and the control system 
has been identified. 

To apply step 8 of the test to our 
computer experiment, cover the cur- 
sor suspected of being controlled with 
a cardboard strip. Control should be 
lost. Cover each cursor. The covered 
one will never pass the test. The other 
steps are easily carried out. 

Concluding Remarks 

Now it is up to you. You can test 
controlled variables involving inten- 
sity, sensation, configuration, 
change, sequence, relationship, 
strategy, principle, and system con- 
cepts having to do with visual, 
auditory, tactile, kinesthetic, and 
other senses. 

Good luck with the programs, and 
good hunting for controlled 
variables. I will be interested to 
receive word about what people are 
doing with the information covered 
in these articles. ■ 



BIBLIOGRAPHY 

Powers, W T, Behavior: The Control ot 
Perception, Aldine Publishing Co, 200 Saw 
Mill River Rd, Hawthorne NY 10532, 1973. 



112 September 1979 © BYTE Publications Inc 




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BYTE September 1979 113 



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BYTE News .... 

lIlllllllllllilllllllllllllllilllllllltltlllllllllllllllllllllllllllltlllllllllllllllllllllllllElllllllllillllllllllllllllllllllllllllllllilllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll 



S-100 8086 AND Z8000 CARDS COMING: At least 6 S-100 product manufacturers are about to 
release 16-bit processor cards for the S-100 bus that use the Intel 8086 and Zilog Z8000. One such 
card has already been announced, a 8086 processor card from Seattle Computer Products Inc, 
Seattle WA. All will conform to the Institute of Electrical and Electronic Engineers (IEEE) S-100 
standard that is soon to be adopted. They will work with most 8-bit memory cards using byte-serial 
read/write. However, for full speed operation you will need either a true 16-bit memory card or a 
modification of your present memory cards. To modify memory cards requires cutting traces, some 
rewiring, and adding some logic circuitry. 

Microsoft has already announced and demonstrated an 8086 BASIC, and is working on a Z8000 
BASIC, as well as other 16-bit software. Digital Research is working on a 8086 version of CP/M. Most 
16-bit software in development will be designed for multiprocessing environments, using real-time 
clocks and interrupt-driven user-inputs. 

CP/M 2.0 TO BE RELEASED SOON: There is no doubt that the most widely used disk operating 
system for microcomputer is CP/M, developed by Gary Kildall of Digital Research, back in 1974. 
Although originally written for the Intel 8080 development system, it was adapted to run on 8080, 
8085 and Z80 systems of many types. Its power and flexibility puts microcomputers in the big leagues 
by providing features and capabilities normally found on the bigger models. 

Gary Kildall is planning to release the 1st major revision to CP/M (Version 2.0). It will use a real- 
time clock and be interrupt-driven. It will support all present CP/M software. Look for its release 
around September 1st. 

RANDOM RUMORS: Matsushita Inc is rumored to be working on a $250 printer which will generate 
"letter quality" type. It will print at 15 characters per second and include a keyboard. Rumors about 
Hewlett-Packard's Personal Computer are getting warmer. It may be introduced in time for the 
Christmas market. Expected to sell in the $2500 area, it will have a 5-inch black and white monitor, 
16 K bytes of programmable memory, BASIC in read-only memory, a built-in thermal printer and 
cassette I/O (input/output). Texas Instruments is developing a 3 or 4-inch Winchester- type disk drive 
to sell for approximately $50. Shugart is about to start delivery on the $70 5-inch floppy disk drive 
made by Matsushita. Infoton, a video terminal manufacturer, is rumored to be about to introduce a 
video terminal which will sell for less than $400 in large quantities. It will use the Zilog Z8 micro- 
processor and have a total of only 16 integrated circuits. All circuitry will be on 1 printed circuit 
card, the power supply will be transformerless, and a special elastomeric keyboard will be used. 

HAND-HELD COMPUTER IN DEVELOPMENT: Matsushita Electrical of Japan and Friends-Amis Inc 
of CA have agreed to develop and produce "the first practical hand-held personal computer." The 
size of a hand-held language translator, the unit could be in production by the end of the year. The 
computer will be able to accept preprogrammed and user programmed memory capsules. Prepro- 
grammed capsules will include information on business, science, language, education, etc. The 
computer will have modular construction, enabling new technology modules to be added as they are 
introduced. Add-ons will include a miniprinter, miniature video display, and a voice synthesizer. 

MICRO-MOUSE CONTEST FINALLY ENDS: The 2 year long "Amazing Micro-Mouse Contest" run 
by the IEEE has finally ended. Although several thousand entries were received, less than 100 
actually ran the maze. The contest's objective was to design a robot-type device which could 
negotiate and learn a maze as it went through. The trials were held at conventions of the IEEE, NCC 
shows and PC-78. 

The ultimate winner was entered by the team of Howard P Katseff and Roy Tramwell from Bell 
Labs, Holmdel NJ. Their mouse ran the 8'/2 by 8'/2-foot maze in just under 30 seconds. It employed a 
Z80 microprocessor with 4 K bytes of read-only memory and 1 K bytes of programmable memory. 
Second prize was taken by the team from Batelle Memorial Institute of Richland WA. Art Boland, 
Ron Dilbeck and Phil Stover's mouse ran the maze in just over 31 seconds. One high performer was 
actually nonprocessor controlled, and ran the maze in just under 40 seconds. 

September 1979 © BYTE Publications Inc 115 



VOICE-OPERATED TV DEMONSTRATED: Sanyo Electric Co recently demonstrated a television 
receiver that responds to voice commands to turn on and off and switch stations. Utilizing a micro- 
processor, the unit compares the voice input to voice patterns stored in memory. The unit has a 30- 
word vocabulary, and can respond to the voices from 2 different people. Furthermore, the voice 
input can be used to play games. Sanyo has not announced any immediate plans for incorporating 
the receiver into its television sets. 

APL FOR MICROCOMPUTERS: Despite a report in an earlier BYTE NEWS column, Quark has 
decided against introducing its APL microcomputer using the Intel 8086 microprocessor. 

JAPANESE MOVING SWIFTLY INTO MICROCOMPUTERS: At least 9 Japanese manufacturers are 
presently manufacturing microprocessor integrated circuits. Approximately 80 different micro- 
processors are being made. Most of them are original designs including advanced features (eg: 
analog-to-digital converters, multiply /divide, counter/timers, etc). Five different 16-bit micro- 
processors are already in production. Furthermore, over a dozen personal computers/trainers are in 
production to support a very strong interest in personal computers in Japan. Thus far only a few 
units are available for export. 

MOTOROLA ANNOUNCES 68000 DELIVERY AND PRICES: Motorola has announced that it expects 
to start shipping limited sample quantities of its new 68000 16-bit microprocessor by the end of the 
year. Single unit price will be $249. Limited production quantities are expected to be available by 
the end of the 1st quarter of 1980, with full production by late 1980. No second source arrangements 
have been finalized. 

75 MEGABYTE WINCHESTER DRIVE RUMORED: At least 6 companies exhibited 8-inch 
Winchester-type drives at the recent NCC show. All of the drives could fit into the same space as an 
8-inch floppy disk drive, and provided from 10 to 45 M bytes of storage. At least 8 companies will be 
delivering these drives by the end of the year, and a 75 M byte version is expected next year. The 
drive should sell for under $2000 in quantity. 

PERSONAL COMPUTER MANUFACTURERS RANK WITH COMMERCIAL DATA PROCESSORS: 
Datamation magazine, in their most recent annual report of the top 50 US companies in the data 
processor industry, disclosed some interesting facts about changes in the computer industry. For the 
1st time a personal computer manufacturer, Tandy, ranked among the top 50 in computer equipment 
sales, and Commodore ranked second among fastest growing companies. Commodore had a 190% 
increase in sales in 1 year, to $75M. Tandy(ranked 43rd)reported computer sales of $105M and total 
company sales of $1,152M resulting in a net income of $76M. The company reported a sales gain of 
only 11.6% (which is about equal to the rate of inflation, and hence could be considered sales 
growth). If Commodore continues to grow at its past year's pace, it too will soon rank among the top 
50. It was reported that 63% of Tandy's computer revenues were from TRS-80 sales, 26% from 
peripherals, 10% from services and 1% from supplies. 

Each data processing company in the top 50 reported sales increases, and most were 20% or 
better. For example, IBM's sales rose almost 28%, while Digital Equipment Corporation's sales rose 
nearly 36%. In fact, none of the traditional maxi or mini makers appear to have been affected by 
personal computers, despite the predictions that were made 2 and 3 years ago. 

MAIL: I receive a large number of letters each month, as a result of this column. If you write to me 
and wish a response, please include a stamped self-addressed envelope. 

Sol Libes 

ACGNI 

1776 Raritan Rd 

Scotch Plains NJ 07076 



116 September 1979 © BYTE Publications Inc 



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Circle 363 on inquiry card. 



BYTE September 1979 117 



Inexpensive Optical 
Paper-Tape Reader 



Brian A Harron 

67-3691 Albion Rd 

Ottawa, Ontario 

CANADA KIT 1P2 



1 microprocessor + 8K BASIC tape 
+4K Startrek tape +45 min = RUN 

This was the terrible equation I had 
to contend with every time I wanted 
to play my favorite game program. It 
would take me 30 minutes to load the 
8 K BASIC paper tape. But not any 
more! 

The solution is a 400 character per 
second paper-tape reader that can in- 
terface to any 8-bit input port of 
almost any microprocessor. It uses 
only 2 integrated circuits and costs 
approximately $15. 

I had always wanted something 
faster than my old reliable Teletype, 
but I never seemed to have the $40 to 
$100 that was needed to buy one of 
the many available kits. I also 
wondered why most of these kits re- 
quired so many integrated circuits to 
accomplish the simple task of latching 
8 bits of data. There are 7 bits 
(sometimes 8 bits) of parallel paper- 
tape data spaced at regular intervals, 
and a sprocket hole for strobing, in- 
cluded at no extra cost. Why not 
design a self-strobing, 8-bit data latch 
using an inexpensive large scale in- 
tegration (LSI) transistor-transistor 
logic (TTL) integrated circuit, the 
INTEL 82127 

The Intel 8212 provides 8 bits of in- 
put, 8 bits of output, strobe, clear, 
and several device enable lines for 
about $5. All I needed to do was to 
optically sense the punched paper- 
tape holes and strobe them into the 
latch at every sprocket hole. 



Although there are several ready- 
made, 8-level, paper-tape-reader 
photodiode assemblies available, I 
decided to construct my own reader 
assembly using individual photo- 
transistors that I already possessed, 
the Motorola type MRD150, which 
are available at most wholesalers for 




Photo 1: View of the paper-tape reader 
showing the light source and the light- 
detecting phototransistors. The spring 
and clamp device keeps the paper tape in 
place. 



approximately $1 each. Their 
miniature size is ideally suited to 0.1 
inch (0.25 cm) spacing. 

Using epoxy, I glued 9 of the 
phototransistors into a 0.5 by 1 inch 
(1.27 by 2.54 cm) piece of 0.100 inch 
(.025 cm) perforated board The 
photocell placed between positions 3 
and 4 (as shown in figure 1) is 
physically reversed so that the active 
surface element of the cell is not in 
line with the other 8 cells. This out- 
of-line detector provides a physical 
delay of the sprocket-hole signal 
which will be signal-conditioned 
later. 

This cell begins to detect light 
through the sprocket hole only after 
all other data holes are fully centered 
over their respective detectors. The 
strobe pulse is now positioned close 
to the center of the pulse from the 
data holes, as shown in the wave- 
forms of figure 2. 

In order to make the strobe pulse as 
insensitive as possible to the variation 
in tape speed caused by moving the 
tape by hand, the sprocket-hole 
detector is amplified by transistor Ql 
and is threshold-detected by ICla, a 
7414 hex Schmitt trigger TTL gate 
(see figure 3, p. 121). The output of 
ICla is then differentiated and level- 
shifted by the capacitor and resistor 
combination Cl, Rl, and R2 such 
that the output of IClb is fast and 
clean even for very slow dark-to-light 
transitions through the sprocket hole. 

The additional gate sections IClc 
and ICld provide buffered outputs of 



118 September 1979 © BYTE Publications Inc 




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BYTE September 1979 119 



the signals STROBE and STROBE , 
which will be used as sense input lines 
to the 8-bit interface port. 

The last 2 sections of the Schmitt 
trigger are configured as a delayed 
power-u p signal that holds the 
CLEAR input pin of the latch at 



ground until the power supply 
voltage has stabilized . 

The DS1 and MD pins of the 8212 
are grounded and the DS2 pin is pin- 
ned to the supply voltage, thus plac- 
ing the 8212 into the strobed latch 
mode of operation. In this way the 8 







































b 

< 


i 


b 


2 

> 


b 

< 


3 

i 


< 


. A, 


b4 
• 


b5 


b6 
• 


br 
• 


be 

• 


a 


K 


r> 


K 


fl 


K 


o 


he 


'K 


fc\ 


fc\ 


fc\ 


C^\ 


^ 





<o 


y 


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\i 




1 


f) 










i 


> 


< 


> 


i 


i 


1 


r 


< 


> 


T 


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ii 


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i> 


T 

ii 


m 


m 


r) 


7 


STROBE 


n 


7 


n 


7 


m 


m 


rh 



Figure 1: Phototransistors in the paper-tape reader. Note the placement of cell between 
bits 3 and 4. The active element is reversed in orientation. 



DATA PULSE 




STROBE PULSE 




STROBE PULSE 
AFTER CONDITIONING 



Figure 2: The strobe pulse is centered in the active signal from the data holes. 



UP: 



DOWN: 



READ: 



IN port# 

RAL 

JNCUP 

IN port # 

RAL 

JC DOWN 

IN port# 

RETURN 



READ INPUT PORT 

SHIFT 1 BIT LEFT 

JUMP TO UP IF CARRY BIT NOT SET 

READ INPUT PORT AGAIN 

SHIFT 1 BIT LEFT 

JUMP TO DOWN IF CARRY BIT SET 

READ INPUT PORT DATA BYTE 

WITH 7 BITS OF DATA IN REG A 



Listing 1: Simple 8080 assembly language program for inputting the data from the 
paper-tape reader. 



bits of data available to the input pins 
DI-0 thru DI-7 are latched through to 
the output pins DO-0 thru DO-7 by 
each positive pulse at the STROBE 
pin. 

Since most paper-tape programs 
used with today's microprocessors 
use only 7 bits of the 8-bit ASCII code 
(bit 8 being vertical parity), it is con- 
venient to use this 8th bit as the 
strobe sense line. When connecting 
the output pins of the latch to the pro- 
cessor input port, simply sele ct strobe 
signal STROBE or STROBE and con- 
nect it to the pin corresponding to bit 
8. 

The software required to read in 
such data is shown in listing 1, where 
bit 8 is the STROBE sense line. When 
bit 8 goes through a low to high to 
low cycle, the data at the input port is 
valid. 

If 8 bits of tape data are required, it 
is necessary to connect the strobe 
sense line to either another input port 
pin or to some other monitor line, 
such as an interrupt or serial input 
line, which can be tested under soft- 
ware control. 

Mechanically, I used a piece of 
0.100 inch (0.025 cm) aluminum sheet 
bent into a U-shape, with an inside, 
bottom width dimension of 1 inch 
(2.54 cm). I used a small piece of clear 
Plexiglas as a hold-down device for 
the tape as it passed over the reader 
photocells. Further improvements 
can be added, such as a motor- 
driven, pinch-roller pull-through, but 
I have had no problems when pulling 
the tape through by hand. As a mat- 
ter of fact, I can stop pulling at any 
time, since the strobe pulse is speed 
insensitive. I plan to eventually add a 
hand crank and a take-up reel to 
avoid the great piles of tape that end 
up on the floor after loading some of 
my larger programs. 

To generate the required illumina- 
tion, I used an automotive lamp (type 
211) mounted 3 inches (7.5 cm) above 
the photocells. Running the lamp on 
5 V provides a good, uniform source 
of light, although it draws about 1 A 
of current. 

This entire project took only 3 
evenings to design and construct, and 
the $15 price tag was a bonus. If you 
are still limited to 10 characters per 
second with your Teletype reader, 
you should seriously consider this 
high-speed paper-tape reader. ■ 



120 September 1979 © BYTE Publications Inc 



+ 5V +5V 



i 



.IOOK 



O^M>^i 



IOOK ^'|4 



m 



+ 5V 



AAAAAAAA 



\ 



IOOK 
(8) 







MRDI50 
^ TYPICAL FOR 8 

PHOTOTRANSISTORS 



+ 5V 



13 



14 



DS2 
DI-0 



CLEAR 
DO-0 



DI-2 



DI-3 



IC2 
8212 



DO-2 



DO-3 



DI-7 DO-7 

DSl MD STROBE 



m 



\ 




V.^Sf' 2N3904 



[>o^h— ^ 



II 



5|\ 6 9|>s. 8 



^ 



/77 



rh 



IOK 



|>oS 



-o 



-o 



o 



-O bit 



£> 



) TO INPUT PORT OF 
PROCESSOR 



-Obit 



-o 



-| > BIT 8 



-j ^> STROBE 



-| ^> STROBE 



IC 


TYPE 


+ 5V 


GND 


2 
1 


8212 
7414 


24 
14 


12 

7 



Figure 3: Schematic diagram of the paper-tape reader, which is capable of 400 characters per second. 

September 1979 © BYTE Publications Irtc 121 



Bock Reviews 



Microcomputer-Based Design 

by John B Peatman 
McGraw-Hill Book Co, 
New York 1977 
540 pages hardcover 
$26.95 



Microcomputer-Based Design by 
John B Peatman is a combination text 
and reference book aimed at 
engineers who wish to learn how to 
design systems using microprocessors. 
It is written not in a dull, dry tone, 
but rather in a light style. The 
minimum required background for 
this text is a rudimentary knowledge 




of logic (ie: transistor-transistor logic 
gates and flip-flops) and the basic 
concepts of computer programming. 
The book develops hardware and 
software design skills upward from 
that point to a practical and useful 
level. A key feature of this book is the 
logical, lucid presentation of 
arguments present in the many 
illustrated design decisions. 

Microcomputer-Based Design is 
divided into 7 chapters and 6 appen- 
dices. The chapters are fairly com- 
plete, in-depth entities and each con- 
tains a set of practical design pro- 
blems and additional references. The 
references may be difficult to find for 
readers without access to an engineer- 
ing library since many of the 
references are articles in engineering 
journals or manufacturers' applica- 
tion notes. 

Chapter 1 is an overview of 
microcomputer applications focusing 
primarily on the distribution of "in- 
telligence" to instruments and tools. 

Chapter 2, "Microcomputer 
Registers and Data Manipulation," 
includes a brief discussion of number- 
ing systems and the various, com- 
monly encountered modes of address- 
ing. This is followed by a good 
presentation of machine language in- 
structions, assembly language, and 
assembly language programming 
techniques. 

Chapter 3 considers computer 
hardware organization. Several dif- 
ferent philosophies of commercially 
available microprocessor families are 
described. The characteristics of 
various logic families are considered 
with an eye towards interconnection 
compatibility. Bus structures and 
their electronic implementation are 
described in some detail. Flags, inter- 
rupts, direct memory acess control 
and programmable timers are also 
described with examples. 

Chapter 4 reviews the various 
characteristics of memory com- 
ponents and systems. Included are 
sections on the implementation of 
main power failure battery backup 
systems and floppy disks. 

Chapter 5 examines peripherals. 
There are sections on input/output 
control and handshaking, timing and 
buffering. There are also discussions 
of specific common microcomputer 
peripherals: keyboards, photo- 
transducers, circuit testers, analog-to- 
digital and digital-to-analog con- 
verters, pressure transducers, optical 



122 September 1979 «-> BYTE Publications Inc 



Circle 328 on inquiry card. 



*0^wyou«s!2!£5£i 



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displays, relay drivers, syn- 
chromotors and printers. Finally, 
there are sections on universal asyn- 
chronous receiver-transmitters 
(UARTs), line drivers, the HPIB-IEEE 
488 bus and self -test hardware. 

Chapter 6 describes the various op- 
tions that exist in hardware and soft- 
ware development packages from 
prototyping boards to disk-based 
operating systems. There is also a 
brief discussion of high-level 
languages for microcomputers. 

Chapter 7 describes in detail the 
algorithms for solutions to several 
common microcomputer software 
problems. Algorithms are described 
to read and to parse a functional 
keyboard input, self-test routines and 
number system conversion and 
manipulations. Real-time program- 
ming constraints are also considered. 

The set of appendices describes the 
characteristics of specific microcom- 
puters. Each appendix covers the ar- 
chitecture and organization of a par- 
ticular processor integrated circuit. 
The rest of the integrated circuit set 
(memory, input/output, etc) is also 
briefly covered. Appendices are in- 
cluded on the 4004, F8, 8080, 6800, 
COSMAC, and PPS-8 processors. It 
is refreshing to see that these appen- 
dices are more than just a reprinting 
of the manufacturer's specification 
sheets. 

On the negative side, there is a 
disturbing absence of discussion of 
any of the high-performance in- 
tegrated circuits that were certainly 
available when this book was 
written. There is also inadequate 
treatment given to bit-slice and 
microprogramming techniques. Soft- 
ware development by emulation is 
also omitted. The balance is, 
however, overwhelmingly positive. 
This is a text which starts off quietly, 
never grows dull, and yet contains a 
great deal of substance. There are sec- 
tions on using esoteric devices like 
first in, first out stacks (FIFOs) that I 
have previously never seen in a 
design text. 

It is a welcome development. I 
recommend this book to advanced 
experimenters, undergraduate 
engineering students and practicing 
engineers. ■ 

Ira Rampil 

2217 Cypress Way 

Apt 15 

Madison WI 53717 



124 September 1979 © BYTE Publications Inc 




Circle 349 on inquiry card. 



BYTE September 1979 125 



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Programming Quickies 



Day of Week and 
Elapsed Time Programs 

W B Agocs, Dept of Physical Sciences 
Kutztown State College, Kutztown PA 19530 

The day of the week, the number of elapsed days of a 
year, and the number of days between 2 dates are infor- 
mation that is required frequently in various types of 
analyses. 

The procedure to determine the day of the week uses 
Zeller's congruence: 



[~ Y 1 




C 




+ 




4 




4 



- -2C}MOD7 



d = {[2.6m-0.2] + K + Y + 



The term m is the month number minus 2. If the month 
is January or February, m is 11 or 12 of the previous year. 
K is the day of the month; C is the century, and Y is the 
year of the century. The value of the square brackets is 
defined as the integer part of the result of evaluating the 
interior expression. 

Day of Week From Date 

The program is so written that corrections to month 11 
or 12 of the previous year are made automatically if the 
month is January (1), or February (2). The program is 
shown in listing 1. Century selection could have been in- 
corporated, but the program is designed for the 20th cen- 
tury. Once the number of the day of the week is obtained 
(with Sunday being day 1), the date and the day are 
printed. 

Matrix Elapsed Time Determination 

The use of a 12 by 31 matrix seems to be the most 
logical method for determining the elapsed days of a 
year, the remaining days in a year, and the day interval 
between 2 dates. 

The program for such a determination is shown in 
listing 2. The MAT A = CON statement in line 50 sets 
each element of the matrix equal to 1. The subroutine in 
statements 440 thru 540 enters 0s into the matrix elements 
which correspond to the months with less than 31 days, 
and then fills the matrix elements with the date's 
numerical location in the year. Thus on return from the 
subroutine, the days elapsed may be printed between 
statements 180 and 190, or between statements 400 and 
410 if desired. Leap year corrections are made at lines 270 
and 440. 

Finally, if the interval between the 2 dates is less than 
or greater than a year (as determined by statement 100), 
the correct year increment is made in statements 230 and 
280. 

The total time interval is determined in statement 180 
or 410, and the result printed at statement 190. 

Text continued on page 129 



126 September 1979 © BYTE Publications Inc Circle 377 on inquiry card. 







Bob admits he thought his computer 
had reached the limit of its capabilities. 
Then he discovered the BASIC Compiler 
from Microsoft. 

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programs are easily linked to assembly 
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Bob believes in giving credit where credit 
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BYTE September 1979 127 



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128 BYTE September 1979 



Circle 211 on inquiry card. 



Text continued from page 126: 

The matrix procedure, with correction for appropriate 
holidays, can be used in conjunction with stock market 
studies when knowledge of the market day interval is 
desired, or when determining if a particular date is a 
market trading day. 



Listing 1: BASIC program for determining the day of the week 
from the date using Zeller's congruence. 



0010 


PRINT "ZELLER'S CONGRUENCE-DAY OF WEEK 




FROM DATE." 


0020 


PRINT "WHAT IS THE DATE-MONTH, DAY, YEAR?" 


0030 


INPUT M,D,Y 


0035 


LET Y1 =Y 


0037 


LETM1 =M 


0040 


IF(M=1)OR(M = 2)THEN 60 


0050 


GOTO 105 


0060 


IF M = 1 THEN 90 


0070 


LET M = 12 


0080 


GOTO 100 


0090 


LET M = 1 1 


0100 


LET Y = Y-1 


0102 


GOTO 110 


0105 


LET M = M-2 


0110 


LET D1 =INT(2.6.M-.2) + D + (Y-1900)+INT((Y-1900)/4) 


0115 


LET D1 =D1 + INT(19/4)-2*19 


0120 


LET D1 =D1-INT(D1/7).7+ 1 


0125 


PRINT "D1 =";D1 


0130 


ON D1 GOTO 140, 150, 160, 170, 180, 190, 200 


0140 


LET A1$ = "SUNDAY" 


0145 


GOTO 210 


0150 


LET A1$ = "MONDAY" 


0155 


GOTO 210 


0160 


LET A1$ = "TUESDAY" 


0165 


GOTO 210 


0170 


LET A1$ = "WEDNESDAY" 


0175 


GOTO 210 


0180 


LET A1$ = "THURSDAY" 


0185 


GOTO 210 


0190 


LET A1$ = "FRIDAY" 


0195 


GOTO 210 


0200 


LET A1$ = "SATURDAY" 


0210 


PRINT "FOR ";M1;"/";D;'7";Y1;" IT IS ";A1$ 


0220 


PRINT 


0230 


END 



Listing 2: BASIC program for using a matrix to determine the 
elapsed time between 2 dates. 

0010 PRINT "MATRIX DETERMINATION OF DAYS BETWEEN 

DATES." 

0020 PRINT "PROGRAMMED APRIL 15, 1979;W. B. 

AGOCS." 

0030 DIMA(12,31) 

0040 DCL S(A()) 

0050 MAT A = CON 

0060 PRINT "WHAT IS THE FIRST MONTH, DATE, YEAR?; 

EXPRESS NUMERICALLY AS 11, 15, 1978." 

0070 INPUT M1, D1, Y1 

0080 PRINT "WHAT IS THE NEXT MONTH, DATE, YEAR?" 

0090 INPUT M2, D2, Y2 

0100 IF Y2-Y1 =0THEN 120 

0110 GOTO 220 

0120 IF Y1/4-INT(Y1/4) = 0THEN 150 

0130 GOSUB450 

0140 GOTO 160 

0150 GOSUB440 

0160 LETS1 =A(M1, D1) 

0170 LET S2 = A(M2, D2) 

0180 LETS3 = S2-S1 

0190 PRINT "INTERVAL BETWEEN ";M1;"/";D1;"/";Y1; 

0195 PRINT " AND ";M2;"/";D2; , 7";Y2;" IS "; 

0200 PRINT S3;" DAYS." 

0210 GOTO 580 

0220 LET S = 

0230 FOR l = Y1 + 1 TO Y2-1 STEP 1 

0240 IF l/4-INT(l/4) = THEN 270 

0250 LETS = S + 365 

0260 GOTO 280 



0270 


LETS = S + 366 




0280 


NEXT I 




0290 


IF Y1/4-INT(Y1/4) = THEN 320 




0300 


GOSUB 450 




0310 


GOTO 350 




0320 


GOSUB 440 




0330 


LETS1 =366-A(M1,D1) 




0340 


GOTO 360 




0350 


LETS1 =365-A(M1,D1) 




0360 


IF Y2/4-INT(Y2/4) = THEN 390 




0370 


GOSUB 450 




0380 


GOTO 400 




0390 


GOSUB 440 




0400 


LETS2 = A(M2,D2) 




0410 


LETS3 = S + S1 +S2 




0420 


GOTO 1 90 




0430 


REM SUB-ROUTINE 




0440 


LET A(2,29) = 




0450 


LET A(2,30) = A(2,31 ) = A(4,31 ) = A(6,31) = 
= A(11, 31) = 


= A(9,31) 


0460 


LET N = 




0470 


FOR 1 = 1 TO 12 STEP 1 




0480 


FOR J = 1 TO 31 STEP 1 




0490 


IF A(I,J) = 1 THEN 510 




0500 


GOTO 530 




0510 


LET N = N + 1 




0520 


LETA(I,J) = N 




0530 


NEXT J 




0540 


NEXT I 




0550 


RETURN 




0560 


PRINT 




0570 


PRINT 




0580 


PRINT "THE END." 




0590 


END ■ 





A Text Loader 
Routine 



Howard Berenbon 

2681 Peterboro 

W Bloomfield MI 48033 



Here is a useful program for the Motorola 6800 
microcomputer. This subroutine allows the loading of 
ASCII text into the desired memory location directly 
from your terminal. It uses the Motorola MIKBUG 
monitor for character input and output. The subroutine 
may be entered beginning at hexadecimal address A060. 
To exit the program simply type a %. 

Hexadecimal Hexadecimal 



Address 




Code 




Mnemonic 


Comments 


A060 


86 


3F 




LDAA #$ 3F 


Load A with ? 


A062 


BD 


EO 


75 


JSR CHAROUT 


Output ? 


A065 


86 


20 




LDAA #$ 20 


Load A with a space 


A067 


BD 


EO 


75 


JSR CHAROUT 


Output space 


A06A 


CE 


- 


- 


LDX #$ 


Load index register with 
desired address 


A06D 


BD EO 
&LOOP 


78 


JSR CHARIN 


Input character 


A070 


A7 


00 




STAA $ 00:X 


Store A indexed 


A072 


08 






INX 


Increment index register 


A073 


81 


25 




CMPA #$ 25 


Compare A with % 


A075 


26 


F6 




BNE &LOOP 


Get another character 


A077 


7E 


E0E3 


JMP MIKBUG 


Return to MIKBUG ■ 



September 1979 © BYTE Publications Inc 129 



A Model of the Brain 
for Robot Control 

Part 4: Mechanisms of Choice 



The essence of a hierarchy is that 
control is top-down. The ultimate 
choices are made at the top, and the 
goals selected at this level are decom- 
posed into action as they filter down 



The ideas presented in this article repre- 
sent the views of the author and not those 
of the Department of Commerce or the 
National Bureau of Standards. 



James Albus 

Project Manager 

National Bureau of Standards 

United States Dept of Commerce 

Washington DC 20234 

through the various levels of the 
hierarchy. For the purposes of our 
discussion, we will define the highest 
level H function in the behavior- 
generating hierarchy of the human 
brain as the will. 

For centuries philosophers and 
theologians have debated the nature 
of the will, particularly the question 
of whether humans have "free" will 
(ie: the freedom to choose goals) or 



whether all choice is merely a reflex- 
ive or predestined response to the en- 
vironment. We shall not presume to 
deal with this question here, other 
than to suggest what types of inputs 
are available to this highest level goal 
selection module. 

By definition much of the input to 
the highest level behavior-generating 
module must come from the highest 
level sensory-processing module. 



TALK 



OBSERVATION 



D 






111 
N 

Z 
<D 
O 
O 


^^c 


IS 

z 

{/) 


LU 






(E 




o 
o 


\ 


1 ~~~"~± 


ft 

a. 



DEVIANT 



NORMAL 



/ 


o 


\ 




/ 
/ 


Ui 

o 
a. 
< 

UJ 






/ 


\ 


\ 


1 



FEAR 



PITY 



AMUSEMENT 



EMOTION 



UNNOTEWORTHY 




MEDICAL 
TREATMENT, 

PSYCHIATRIC 
TREATMENT 

INCARCERATION 



TOLERANCE 



SYMPATHY 




WILL 



LAUGHTER 



L- POKE FUN 



•- CONTINUE 
ON-GOING 
ACTIVITY 



-\ 



•1 



°5 

> a. 
< uj 

X 2 

LiJ UJ 



Figure 1: An action (such as a person talking to a flower) may be recognized as either familiar or unfamiliar. If an action is noted as 
familiar, then it can be considered unnoteworthy and will be ignored. If the action is considered deviant, further processing will take 
place to determine reactions to the action. 



130 September 1979 © BYTE Publications Inc 



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BYTE September 1979 131 



This is the level at which the overall 
result of the entire sensory processing 
operation is evaluated as being good 
or bad, rewarding or punishing, satis- 
fying or frustrating. In humans, this 
function is performed by what are 
commonly called the emotions. It has 
long been recognized that emotions 
play a crucial role in the selection of 



About the Author 

Dr ]ames S Albus worked for NASA from 
1957 to 1972 designing optical and electronic 
subsystems for over 15 spacecraft, and for one 
year managed the NASA Artificial Intelligence 
Program. Since 1973 he has been with the 
National Bureau of Standards where he has 
received several awards for his work in 
advanced computer control systems for in- 
dustrial robots. He has written a survey article 
on robot systems for Scientific American 
(February 1976) and his Cerebellar Model 
Arithmetic Computer won the Industrial 
Research Magazine IR-100 Award as one of the 
100 most significant new products of 1975. He 
is also the author of People's Capitalism: The 
Economics of the Robot Revolution which is 
published by New World Books, 4515 Saul Rd, 
Kensington MD 20795. 



behavior. We tend to practice that 
which makes us feel comfortable and 
avoid what we dislike. Our behavior- 
generating hierarchy normally seeks 
to prolong, intensify, or repeat those 
behaviors which give us pleasure or 
make us feel happy or contented. We 
normally seek to terminate, diminish, 
or avoid those behavior patterns 
which cause us pain, or arouse fear or 
disgust. 

In the past 25 years it has become 
known that the emotions are 
generated in localized areas, or com- 
puting centers, in the brain. For ex- 
ample, the posterior hypothalamus 
produces fear, the amygdala gen- 
erates anger and rage, the insula com- 
putes feelings of contentment, and the 
septal regions produce joy and ela- 
tion. The perifornical nucleus of the 
hypothalamus produces punishing 
pain, the septum pleasure, the 
anterior hypothalamus sexual 
arousal, and the pituitary computes 
the body's response to danger and 
stress. These emotional centers, along 



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with many others, make up a com- 
plex of about 53 regions linked 
together by 35 major nerve bundles. 
This entire network is called the lim- 
bic system. Additional functions per- 
formed in the limbic system are the 
regulation of hunger and thirst per- 
formed by the medial and lateral 
hypothalamus, the control of body 
rhythms such as sleep-awake cycles 
performed by the pineal gland, and 
the production of signals which con- 
solidate (ie: make permanent) the 
storage of sensory experiences in 
memory performed by the hippo- 
campus. This last function allows the 
brain to be selective in its use of 
memory by facilitating the permanent 
storage of sensory experiences to 
which the emotional evaluators 
attach particular significance (eg: 
close brushes with death, punishing 
experiences, etc). 

Input to the limbic system emo- 
tional centers consists of highly pro- 
cessed sensory -data such as the names 
of recognized objects, events, rela- 
tionships, and situations, such as the 
recognition of success in goal achieve- 
ment, the perception of praise or 
hostility, or the recognition of 
gestures of dominance or submission 
transmitted by social peers. These in- 
puts are accompanied by such modi- 
fier variables as confidence factors 
derived from the degree of correlation 
between predicted and observed sen- 
sory input. 

Sensory processing at the level of 
the emotions is heavily influenced by 
contextual information derived from 
internal models and expectations at 
many different levels in the proces- 
sing hierarchy. If a painful stimulus is 
perceived as being associated with a 
nonfear producing source, we may 
attack the pain causing agent. If, 
however, the perceived source of pain 
also induces fear, we may flee. 

Similarly if an observed event such 
as a person talking to a flower is per- 
ceived as deviant, then this input to 
the emotions, along with other 
recognized qualifier variables such as 
the person is a) eccentric, b) retarded, 
or c) dangerously psychotic, will 
cause the emotions to output a) 
amusement, b) pity, or c) fear, 
respectively. Amusement input to the 
behavioral goal selecting module may 
lead to laughter, poking fun, or 
ridicule. Pity input to the will may 



132 September 1979 © BYTE Publications Inc 



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evoke a behavioral pattern of sym- 
pathy. Fear may evoke an attempt to 
secure medical or psychiatric treat- 
ment, or incarceration. 

If, however, a person talking to a 
flower is recognized as perfectly nor- 
mal, then the emotions will give no 
indication that the event is particu- 
larly worthy of attention, or that 
there exists any need to deviate from 
whatever behavior is presently being 
executed. These relationships are 
described graphically and symboli- 
cally in figure 1. 

In this model the standards of nor- 
malcy and deviance are clearly in the 
eye of the beholder, or at least in the 
expectations and beliefs stored in the 
processing-generating hierarchy. In 
many ways the emotional evaluators 
are even more dependent on internal 
beliefs than externally observed facts. 
This is particularly true in the case 
where a person's belief structure dis- 
counts the reliability or moral worth 
of the physical senses, as is 
characteristic of philosophical con- 
structs derived from gnosticism or 
asceticism. 

Thus the emotions, just as any 
other sensory processing module in 



the brain, simply compute a G func- 
tion on the D vector that they input 
to produce the Q vector that they 
output. In simple creatures the emo- 
tional output vector may be restricted 
to a few components such as good- 
bad, pleasure-pain, etc. In higher 
forms the emotional output is a 
highly multidimensional vector with 
many faceted components such as 
love, hate, jealousy, guilt, pride, 
disgust, etc. Part of this Q output 
may simply produce feelings (ie: joy, 
sadness, excitement, fear, etc). 
However, most of the Q output 
directly or indirectly provides F input 
to the highest level H function, the 
will. 

Output from the emotional centers 
is known to be of two types: one con- 
sists of signals on nerve fibers; the 
other consists of hormones and 
chemical transmitters which convey 
their messages (Q vector values) via 
fluid transport mechanisms. 

What the G and H functions of the 
emotions and will are, and where 
they come from is a matter of hot 
dispute. One recent theory proposed 
by sociobiology is that they are gene- 
tically determined, derived from in- 



formation stored in the DNA 
molecule, as the result of millions of 
years of natural selection. This theory 
argues that innate behavior-selecting 
mechanisms have evolved so as to 
maximize the Darwinian fitness (the 
expected number of surviving off- 
spring) of their possessors. 

The incidence of behavior in many 
different species from insects to birds 
to mammals corresponds closely to 
mathematical predictions derived 
from genetics and game-theory 
analyses of strategies for maximizing 
the probability of gene propagation. 
Even cooperative or altruistic 
behavior such as that of the worker 
bee, and ritualized behavior in animal 
contests and courtship, can in many 
cases be explained by genetic 
arguments. However, the evidence 
for this theory is much stronger for 
insects than for higher forms, and the 
opinion that human emotions are 
transmitted genetically is not widely 
held. 

A competing theory put forward 
by behaviorists is that in higher forms 
the evaluator functions of the emo- 
tion and the selector functions of the 
will are mostly learned, perhaps even 



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PEOPLES' CAPITALISM 

The Economics of the 

ROBOT REVOLUTION 

by 

JAMES S. ALBUS 

Jeffersonian democracy applied to the 
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134 



Seplember 1979 © BYTE Publications Inc Circle 320 on inquiry card. 



Circle 282 on inquiry card. 




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imprinted, during the early years of 
development. Certainly many of the 
emotional evaluations and behavior 
selection rules in the human brain are 
culturally determined, derived from 
religious teachings defining good and 
evil, or from social conventions 
defining duty, fairness, etiquette, and 
legality. These fundamental rules of 
opinion and behavior are instilled in 
the young by parents, educators, and 
religious and state authorities. They 
are reinforced throughout life by peer 
group pressure, as well as by church 
and civil sanctions. 

There are, of course, many persons 
who would disagree with both of 
these theories. Perhaps the most 
widespread opinion (which until 
recent years was virtually unchal- 
lenged) is that the human will and its 
emotional evaluator inputs are non- 
mechanistic in nature and therefore 
unknowable in some fundamental 
sense. Many would even claim that 
emotions and will are subject to, or 
controlled by, spiritual and super- 
natural forces. For example, the doc- 
trine of original sin states that the 
highest level behavior selecting 
mechanism, the human will, is 



basically defective because of the 
disobedience of Adam and Eve, and 
except for divine intervention is 
under the power of evil or satanic 
forces. The literature surrounding the 
age old controversy over free will 
versus predestination centers largely 
on the role of the Divinity (or the 
stars, or fates) in the determination of 
human behavior. Most cultures view 
the conscience (ie: the emotional 
evaluator for right and wrong or 
good and evil) as a divine gift or 
manifestation of the indwelling of the 
spirit of God. 

Clearly the emotions and will are a 
very basic (some would say prim- 
itive) and compelling part of our 
behavioral mechanism. Carl Sagan 
calls them the Dragons of Eden. 
Humans are often driven, sometimes 
beyond rational justification, to 
heroic feats of courage or physical 
endurance by the behavior rules of 
duty or the emotions of love, pride, 
guilt, jealousy, and hate. 

Whatever their origins, the G func- 
tions of our emotions and the H func- 
tions of the will can be modeled. 
They are rule based, and the rules 
are, for the most part, clearly defin- 



ed. In many cases these rules are even 
written down as systems of moral 
philosophy, ethics, or rules of social 
behavior such as Emily Post's Book of 
Etiquette. 

Nothing so complex need be 
modeled for the highest level G and H 
modules of a robot for many years. 
Nevertheless, every robot needs some 
sort of highest level evaluator and 
goal selector function in order to ex- 
hibit any sort of autonomous be- 
havior. At what point in the spectrum 
of multidimensional sophistication 
we choose to dignify an evaluator 
function with the term emotion, or 
goal selection function with the term 
will, is not clear. What is clear is that 
simple approximations to the func- 
tions computed by the emotions and 
the will can be moduled by CMAC G 
and H functions operating on input 
vectors and computing output vec- 
tors. The degree of sophistication and 
complexity of the modeling is limited 
only by the ingenuity and resources 
of the modeler. 

The interdependency of the pro- 
cessing and generating hierarchies 
suggests at least 3 distinct modes of 
operation. 



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Acting — The Task Execution 
Mode 

In the task execution mode the 
motor-generating hierarchy is com- 
mitted to a goal, which it decomposes 
into subgoals, sub-subgoals, and 
finally into action primitives. In this 
mode the sensory-processing hier- 
archy is primarily engaged in pro- 
viding feedback; first to aid in se- 
lecting the goal, then to steer the goal 
decomposition process, and finally to 
direct the output drive signals to the 
muscles (or actuators) so as to follow 
a success trajectory. 

Consider a simple, everyday goal 
such as the fixing of a leaking faucet. 
First, the sensory processing system 
must recognize the fact that the faucet 
is leaking. This information is then 
evaluated by the emotions as some- 
thing that needs attention. This 
evaluation is passed on to the will, 
where the rules of what ought to be 
done and under what circumstances 
reside. If there are no higher priority 
items vying for the attention of the 
will, then the goal <fix faucet > may 
be selected. Once this occurs, the 
behavior generating hierarchy will be 
committed to decompose this goal 
into a sequence of actions. 

At each instant of time t k the 
sensory-processing module at each 
hierarchical level extracts feedback 
vectors F* required by the H 
behavior-generating modules at each 
level for goal decomposition. At the 
instant t when the goal is selected, 
the feedback F? at the various levels 
causes the selection of the initial 
subgoal decompositon P°. This deter- 
mines the initial direction of the tra- 
jectories T P ,. on their way toward the 
goal state. As the task proceeds, the 
recognition of subgoal completions 
and/or unanticipated obstacles trig- 
gers the selection of the proper se- 
quence of actions directed toward the 
goal achievement. 

The entire set of trajectories 
T ^describes the sequence of internal 
states of the brain which underlie and 
give rise to the observable phen- 
omena of purposive behavior. These 
are the deep structure of behavior. 
Only the output trajectory, the ter- 
minal or bottom level trajectory, is 
manifested as overt action. The ex- 
tent to which the trajectories T P] . are 
independent of feedback is the extent 
to which behavior is preprogrammed. 
The extent to which the feedback 
pulls the T P . trajectories along predic- 



table paths to the goal state is the ex- 
tent to which behavior is adaptive. 
For some goals, such as hunting for 
prey or searching for breeding ter- 
ritory, the selection of the goal 
merely triggers migratory searching 
behavior which continues until feed- 
back indicates that the goal is near at 
hand. For such goals, behavior is in- 
definite and highly feedback depen- 
dent. For other goals, such as 
building a nest, making a tool, 
courting a mate, or defending a 
territory, behavior is more inner- 
directed, requiring only a few sensory 
cues for triggers. 

In either case, while in the acting 
mode the sensory data flowing in the 
sensory-processing hierarchy is 
highly dependent on (if not directly 
caused by) the action itself. If the 
action is speech, the sensory- 
processing hierarchy is analysing 
what is spoken, and provides feed- 
back for control of loudness, pitch, 
and modulation. If the action is 
physical motion, data from vision, 
proprioception, and touch sensors are 
all highly action dependent, and the 
sensory analysis is primarily directed 
toward servo control of the action 
itself. 

In the action mode, the M,- 
associative memory modules provide 
context in the form of predicted data 
to the sensory-processing modules in 
order to distinguish between sensory 
data caused by motion of the sensors 
and that caused by motion of the en- 
vironment. What is predicted is 
whatever was stored on previous ex- 
periences when the same action was 
generated under similar circum- 
stances. This allows the sensory- 
processing hierarchy to anticipate the 
sensory input and to detect more 
sophisticated patterns in the sensory 
data than would otherwise be possi- 
ble. 

Observing — The Sensory 
Analysis Mode 

A second mode of operation of the 
crosscoupled hierarchy is the analysis 
of sensory data from external sources 
not primarily caused by action of the 
behavior-generating hierarchy. For 
example, when listening to a concert, 
a speech, or a play, there is little ac- 
tion going on in the muscles and 
motor neurons. The lower levels of 
behavior-generating hierarchies are 
quiescent, or set to a constant value, 
or given a command to execute an 



138 September 1979 © BYTE Publications Inc 




More than meets the eye. 



The new Series 5000 is mighty for its size. 
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BYTE September 1979 139 



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overlearned task which can be carried 
out without any assistance from the 
upper levels. 

The sensory-processing hierar- 
chies, however, are very busy. They 
are filtering and predicting, recogniz- 
ing patterns and trajectories, locking 
on to rhythms and harmonious 
periodicities, and tracking targets of 
attention. Predictions generated by 
the M modules are clearly required 
for these types of analyses, whether 
or not the organism is engaged in 
physical activity. This suggests that 
the upper levels of the behavior- 
generating hierarchies (which are not 
currently required for generating 
behavior) might be used instead to 
generate hypotheses and subhypo- 
theses which in turn produce context 
and predictions to aid the sensory- 
processing hierarchy in the recogni- 
tion, analysis, and understanding of 
incoming sensory data. 

At each level hypotheses which 
generate T K predictions that match or 
track the T E sensory data trajectories 
will be confirmed. If the hypothesized 
T K trajectories are only close to the T E 
observations, they can be pulled by 
error signal feedback TV from the pro- 
cessing hierarchies. When a hypo- 
thesis is successful in generating 
predictions which match the sensory 
data stream, the loop at that level 
locks onto the sensory data. When 
lock-on is simultaneously achieved at 
many different levels, we can say that 
the processing-generating hierarchy 
"understands" the incoming data (ie: 
it can follow and predict it at many 
different levels). The depth of 
understanding depends upon how 
many levels lock onto the sensory 
data stream. The accuracy of 
understanding depends upon how 
precisely the hypotheses track and 
predict the incoming sensory data. 

It is easier to follow a trajectory 
than to reproduce it. When observing 
a procedure, the generating hierarchy 
merely needs to produce hypotheses 
which are in the right vicinity so that 
they can be synchronized with the 
sensory input. Uncertainties at 
branch points in T P , do not matter 
greatly because errors are quickly 
corrected by comparing T fi . with T £l .. 

On the other hand, reproducing a 
procedure requires that the H func- 
tions be capable of generating T Pl tra- 
jectories which are quite precise over 
their entire length. They must not 
wander outside of the success 



envelope or miss any critical branch 
points. Needless to say, the latter is a 
much more exacting computational 
problem, and offers an explanation 
for why a student may be able to 
follow the reasoning of his professor's 
lecture, but is unable to pass an exam 
without additional drill and practice. 

Attention 

The directing or focusing of atten- 
tion is essentially a purposive action 
whose goal is to optimize the quality 
of the sensory data. The basic 
elements of attention are orienting 
(positioning the body and sensory 
organs so as to facilitate the gathering 
of data) and focusing (blocking out 
extraneous or peripheral information 
so that the sensory processing system 
can bring all of its capacities to bear 
on data that is relevant to the object 
of attention). The orienting element is 
simply a behavioral task or goal to 
acquire and track a target. The fo- 
cusing element is a filtering problem 
which can be solved by a hypothesis 
or goal decomposition which evokes 
the appropriate masks or filter func- 
tions from the R, modules so as to 
block out all but the relevant sensory 
input data. 

Thus, attending is a combination of 
observing and acting. It is primarily a 
sensory analysis mode activity, with 
a stong assist from the task execution 
mode. 

Imagining — The Free- 
Running Mode 

A third distinct mode of operation 
occurs when the upper levels of the 
processing-generating hierarchy are 
largely disconnected from both motor 
output and sensory input. In this 
mode high-level hypotheses T P . may 
be generated, and predicted sensory 
data T fi| recalled. In the absence of 
sensory input from the external en- 
vironment, these recalled trajectories 
make up all of the information flow- 
ing in the sensory-processing hier- 
archy. The processing modules G, 
operate exclusively on the internally 
recalled R, trajectories producing 
T Q ,experiences and T Fi feedback. The 
^trajectories act on the generating 
hierarchy so as to modify and steer 
the Xs, trajectories creating new 
hypotheses T P ,.. The system is free 
running, guided only by stored ex- 
periences M,, learned interpretations 
G„ and practiced skills H„ for 



140 



September 1979 © BYTE Publications Inc 



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BYTE September 1979 141 



generating strings of hypotheses and 
decomposing goals and tasks. The 
upper levels of the crosscoupled 
hierarchy are, thus, imagining (ie: 
generating and analyzing what would 
be expected if certain hypothesized 
goals and tasks were to be carried 
out). 

Imagination is based on stored ex- 
periences and driven by hypothesized 
actions. It is constrained in large 
measure by the knowledge frames, 
world models, expected values, and 
belief structures (IF I do this, THEN 
such and so will happen) embedded in 
the upper levels of the cross-coupled 



processing-generating hierarchy. 

If we attempt to hypothesize some 
action X which lies outside of the 
neighborhood of generalization of 
prior experience, we get no recalled R, 
vectors from memory M,. In this case 
we say "we cannot imagine what X 
would be like." 

One of the functions of the free- 
running mode is to remember or 
recall past experiences by hypothesiz- 
ing the same goals as when the ex- 
perience was recorded. Thus, in our 
imagination we can reach back and 
relive experiences, recall events, and, 
hence, remember facts and relation- 



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ships from our past. Imagination, 
however, is not limited to duplication 
of past experiences. We can also re- 
arrange sections of learned trajec- 
tories to create experiences in our 
minds which never occurred. We can 
string together trajectories in new 
combinations or insert new modifier 
variables in various hypothesis vec- 
tors. We can watch a bird fly and 
substitute a "self" variable in place of 
the bird to imagine ourselves soaring 
through the sky. We can listen to a 
story of adventure and imagine 
ourselves in the place of one of the 
characters. Imagination allows us to 
hypothesize untried actions and, on 
the basis of M functions learned 
during previous experiences, to 
predict the outcome. 

Planning 

Imagination gives us the ability to 
think about what we are going to do 
before committing ourselves to ac- 
tion. We can try out, or hypothesize 
prospective behavior patterns, and 
predict the probable results. The 
emotions enable us to evaluate these 
predicted results as good or bad, 
desirable or undesirable. 

Imagination and emotional evalu- 
ators together give us the capability 
to conduct a search over a space of 
potential goal decompositions and to 
find the best course of action. This 
type of search is called planning. 

When we plan, we hypothesize 
various alternative behavior trajec- 
tories and attempt to select the one 
that takes us from our present state to 
the goal state by the most desirable 
route. Imagined scenarios which pro- 
duce positive emotional outputs are 
flagged as candidate plans. Favorably 
evaluated scenarios or plans can be 
repeatedly rehearsed, reevaluated, 
and refined prior to initiation of 
behavior-producing action. 

Imagined scenarios which produce 
negative evaluation outputs will be 
avoided if possible. In some situa- 
tions it may not be possible to find a 
path from our present state to a goal 
state, or at least not one which pro- 
duces a net positive evaluation. 
Repeated unsuccessful attempts to 
find a satisfactory, nonpunishing 
plan, particularly in situations 
recognized as critical to one's well- 
being, correspond to worry. 

One of the central issues in the 
study of planning is the search 
strategy, or procedure, which dictates 



142 September 1979 © BYTE Publications Inc 



Circle 47 on inquiry card. 



ANOTHER FIRST FROM 
MOUNTAIN HARDWARE. 

SUPERTALKER. 



YOUR APPLE. 

SuperTalker allows you 
to add the dimension of 
human speech output in 
your computer programs. 
Add voice to games. Pro- 
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warnings under program con- 
trol as an enunciator in com- 
mercial security or control rooms. 
Create educational programs that 
verbally coach the student. 
THE SUPERTALKER SYSTEM. 
SuperTalker is a new Mountain 
Hardware peripheral system which 
allows the Apple II computer to output exception- 
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speaker under program control. Output may also 
be directed through any RA. or stereo system. 
Initially, spoken words are digitized into RAM 
memory through the system microphone. Speech 
data in RAM may then be manipulated like any 
other stored data. 
A COMPLETE PACKAGE. 
The SuperTalker peripheral system consists of: 
The SuperTalker peripheral card which plugs into 



FOR YOUR 
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OPERATING SYSTEMS. 
In order to achieve maximum 
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SuperTalker Disk Operating 
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It also provides a preparation pro- 
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program routines are provided 
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TEACH YOUR COMPUTER TO TALK. 
For $279 assembled and tested, SuperTalker 
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Apple II is a trademark of Apple Computer, Inc. 



Circle 257 on inquiry card. 



BYTE September 1979 143 



which of the many possible hypo- 
theses should be evaluated first. In 
most cases, the search space is much 
too large to permit an exhaustive 
search of all possible plans, or even 
any substantial fraction of them. The 
set of rules for deciding which 
hypotheses to evaluate, and in which 
order, are called heuristics. 

Heuristics are usually derived in an 
ad hoc way from experience, acci- 
dent, analogy, or guesswork. Once 
discovered, they may be passed from 
one individual to another, and from 
one generation to another by 
teaching. 



Historically, artificial intelligence 
researchers have been fascinated by 
the subject of heuristics. At least a 
portion of this interest is a result of 
their recursive nature. A heuristic is a 
procedure for finding a procedure. 
When this recursion is embedded in a 
cross-coupled processing-generating 
hierarchy with the rich complexity of 
the human brain, it becomes clear 
why the thoughts and plans of 
humans are filled with such exquisite 
subtleties, and curious, sometimes in- 
sidious reasoning. It also provides 
some insight into the remarkable 
phenomenon of self-consciousness 




Built-in Interface for 
TRS-80, PET and Apple II Computers 



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interface. Take it home, plug it in and 
start printing. We even supply the 
cable and connector. 

There are two models: The EX-801 
prints upper and lower case alpha- 
numeric characters and all the 



graphic symbols used by your com- 
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(213) 245-9244 • TWX: 910-497-2283 



(ie: a computing structure with the 
capacity to observe, take note of, 
analyze, and, to some extent, even 
understand itself.) 

Much of the artificial intelligence 
research in planning and problem 
solving has its origins and theoretical 
framework based on simple board 
games where there are a finite 
(although sometimes very large) 
number of possible moves. The 
discrete character of such games, 
together with the digital nature of 
computers, led naturally to the 
analysis of discrete trees, graphs, and 
search strategies for such structures. 

Planning in a natural environment 
is much more complex than searching 
discrete trees and graphs. In the study 
of planning in the brain it is necessary 
to deal with the continuous time- 
dependent nature of real world 
variables and situations. States are 
not accurately represented as nodes in 
a graph or tree; they are more like 
points in a tensor field. Transitions 
between states are not lines or edges, 
but multidimensional trajectories 
(fuzzy and noisy at that). In a natural 
environment, the space of possible 
behaviors is infinite. It is clearly im- 
possible to exhaustively search any 
significant portion of it. Furthermore, 
the real world is much too unpredic- 
table and hostile, and wrong guesses 
are far too dangerous to make ex- 
ploration practical outside of a few 
regions in which behavior patterns 
have had a historical record of suc- 
cess. Thus behavior, and hence im- 
agination and planning, is confined to 
a relatively small range of possi- 
bilities, namely those behavior and 
thought patterns which have been 
discovered to be successful through 
historical accident or painful trial and 
error. Both the potential behavior 
patterns and the heuristics for selec- 
ting them are passed from one genera- 
tion to another by parents, educators, 
and civil and religious customs. 

Daydreaming or Fantasizing 

The fact that the imagination can 
generate hypothetical scenarios with 
pleasurable emotional evaluations 
makes it inevitable that such 
scenarios will, upon occasion, be 
rehearsed for their pleasure-pro- 
ducing effect alone. This is a pro- 
cedure that can only be described as 
daydreaming or fantasizing. 

When we daydream we allow our 
hypothesis generators to drift 



144 September 1979 © BYTE Publications Inc 



Circle 13 on inquiry card. 



S reasons why you should not buy 



the electric pencil II 

^* ° 1978 Michael Shrayer 

Check the appropriate box(es): 

You love typing the same copy 20 thousand times a day. 

□ Your secretary can type 250 words per minute. 

□ You're dying to spend $15,000 on a word processing system, just for the 
tax investment credit. 

□ All your capital assets are tied up in a 10-year supply of correction fluid. 

□ You never commit a single thought to paper. 

If you have checked one or more boxes, you do not need The Electric Pencil. 
On the other hand, you may want to join the thousands of people who haven't 
checked a single box. 



TM 




The Electric Pencil II is a Charac- 
ter Oriented Word Processing System. 
This means that text is entered as a 
string of continuous characters and is 
manipulated as such. This allows the 
user enormous freedom and ease in the 
movement and handling of text. Since 
line endings are never delineated, any 
number of characters, words, lines or 
paragraphs may be inserted or deleted 
anywhere in the text. The entirety of 
the text shifts and opens up or closes 
as needed in full view of the user. The 
typing of carriage returns or word 
hyphenations is not required since 
lines of text are formatted automatic- 
ally. 

As text is typed and the end of a 
line is reached, a partially completed 
word is shifted to the beginning of the 
following line. Whenever text is insert- 
ed or deleted, existing text is pushed 
down or pulled up in a wrap around 
fashion. Everything appears on the 
video display as it occurs, which elim- 
inates guesswork. Text may be review- 
ed at will by variable speed scrolling 
both in the forward and reverse direc- 
tions. By using the search or search 
and replace functions, any string of 
characters may be located and/or re- 
placed with any other string of charac- 
ters as desired. 

Numerous combinations of 
line length, page length, line 
spacing and page spacing permit 
automatic formatting of any 
form. Character spacing, bold 
face, multicolumn and bidirec- 
tional printing are included in 
the Diablo versions. Multiple 
columns with right and left justified 
margins may be printed in a single pass. 

Wide screen video 

Versions are available for Imsai 
VIO video users with the huge 80x24 
character screen. These versions put al- 
most twice as many characters on the 



CP/M versions 

Digital Research's CP/M, as well as 
its derivatives, including IMDOS and 
CDOS, and Helios PTDOS versions are 
also available. There are several NEC 
Spinwriter print packages. A utility 
program that converts The Electric 
Pencil to CP/M to Pencil files, called 
CONVERT, is only $35. 

Features 

• CP/M, \MDOSand HELIOS compatible 

• Supports four disk drives 

• Dynamic print formatting 

• DIABLO and NEC printer packages 

• Multi-column formatting in one pass 

• Print value chaining 

• Page-at-a-time scrolling 

• Bidirectional multispeed scrolling con- 
trols 

• Subsystem with print value scoreboard 

• Automatic word and record number 
tally 

• Cassette backup for additional storage 

• Full margin control 

• End-of-page control 

• Non-printing text commenting 

• Line and paragraph indentation 

• Centering 

• Underlining 

• Bold face 

Upgrading policy 

Any version of The Electric Pencil 



Have we got a version 
for you? 

The Electric Pencil II operates 
with any 8080/Z80 based microcom- 
puter that supports a CP/M disk sys- 
tem and uses an Imsai VIO, Processor 
Tech. VDM-1, Polymorphic. VTI, Solid 
State Music VB-1B or Vector Graphic 
video interface. REX versions also 
available. Specify when using CP/M 
that has been modified for Micropolis 
or North Star disk systems as follows: 
for North star add suffix A to version 
number; for Micropolis add suffix B, 
e.g.,SS-IIA, DV-IIB. 



Vers. 


Video 


Printer 


Price 


SS-II 


SOL 


TTY or similar 


$225 


SP-ll 


VTI 


TTY or similar 


225 


SV-II 


VDM 


TTY or similar 


225 


SR-II 


REX 


TTY or similar 


250 


Sl-ll 


VIO 


TTY or similar 


250 


DS-II 


SOL 


Diablo 1610/20 


275 


DP-II 


VTI 


Diablo 1610/20 


275 


DV-II 


VDM 


Diablo 1610/20 


275 


DR-II 


REX 


Diablo 1610/20 


300 


Dl-ll 


VIO 


Diablo 1610/20 


300 


NS-II 


SOL 


NEC Spinwriter 


275 


NP--II 


VTI 


NEC Spinwriter 


275 


NV-II 


VDM 


NEC Spinwriter 


275 


NR-II 


REX 


NEC Spinwriter 


300 


Nl II 


VIO 


NEC Spinwriter 


300 


SSH 


SOL 


Helios/TTY 


250 


DSH 


SOL 


Helios/Diablo 


300 




MICHAEL SHRAYER SOFTWARE, INC 

1253 Vista Superba Drive 

Glendale, CA. 91205 

(213)956-1593 



may be upgraded at any time by sim- 
ply returning the original disk or cas- 
sette and the price difference between 
versions, plus $15 to Michael Shrayer 
Software. Only the originally purchas- 
ed cassette or diskette will be accepted 
for upgrading under this policy. 



Attention: TRS-80 Users! 

The Electric Pencil has been de- 
signed to work with both Level I 
(16K system) and Level II mod- 
els of the TRS-80, and with vir- 
tually any printer you choose. 
Two versions, one for use with 
cassette, and one for use with 
disk, are available on cassette. 
The TRS-80 disk version is easily tran- 
sferred to disk and is fully interactive 
with the READ, WRITE, DIR, and 
KILL routines of TRSDOS 2.1. 
Version Stora ge Price 

TRC Cassette $100. 
TRD Disk $150. 



ill! 



Demand a demo from your dealer ! 



Circle 319 on inquiry card. 



BYTE September 1979 145 



Circle 77 on inquiry card. 



PET PRINTER ADAPTER 



GET HARD COPY FROM YOUR 
COMMODORE PET USING A 
STANDARD RS-232 PRINTER 



iinnn "»»> nnnn ^™ 



1200B 



1200C 



The CmC ADA 1200 drives an 
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manuscripts, mailing labels, 
tables of data, pictures, in- 
voices, graphs, checks, needle- 
point patterns, etc., using a 
standard RS-232 printer or 
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$98.50 ADA1200B 

Assembled and tested 

$169.00 

With case, power supply 
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ADA1200C 



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Add $3.00 for postage and handling per order. 

O CONNECTICUT microCOMPUTER 

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La (203I 775 9659 TLX: 7104560052 



wherever our emotional evaluators 
pull them. Our imagination gravi- 
tates toward those trajectories which 
are emotionally most rewarding. 
Some of the most pleasurable 
scenarios we can imagine are 
physically impossible, impractical, or 
socially taboo. Most of us recognize 
these as fantasies and never attempt 
to carry them out. However, once a 
person adopts the intent to carry out 
a fantasy, it ceases to be a dream and 
becomes a plan. 

Thus, planning and daydreaming 
are closely related activities, differing 
principally in that planning has a 
serious purpose and involves an in- 
tent to execute what is finally selected 
as the most desirable of the alter- 
native hypotheses. 

This model suggests that dreaming 
while sleeping is similar in many 
respects to daydreaming. The prin- 
cipal difference in night dreaming 
seems to be that the trajectories 
evoked are more spasmodic and ran- 
dom, and are not always under the 
complete control of the emotions and 
will. 



Creativity 

The notion of planning or dis- 
covering procedures for achieving 
goals leads inevitably to the issue of 
creativity. If we assume that most of 
the H, G, and M functions in the 
processing-generating hierarchy are 
learned, then where is the creativity? 
Is creativity merely an illusion 
generated by the recursion of pro- 
cedures for discovering procedures? 

Certainly we as humans like to 
think of ourselves as creative. But 
what are we doing when we create 
something new? Typically we borrow 
an idea from here, put it together 
with another from there, and give it a 
different name. We take a familiar 
behavioral trajectory, add a tiny 
variation, and claim that we have 
discovered something completely new 
— a new dance step, dress style, 
song, or idea. Seldom, however, are 
any of these more than the slightest 
deviation from a preexisting pro- 
cedure or behavioral trajectory. To 
quote Ecclesiastes: "There is nothing 
new under the sun." 

True creativity, in the sense of the 



invention of an entirely new behav- 
ioral trajectory, is extremely rare, if it 
ever occurs at all. Furthermore, it is 
highly doubtful that a truly creative 
act would be recognized if it ever did 
occur. Our processing-generating 
hierarchies cannot lock on to sensory 
input patterns which are totally dif- 
ferent from everything that is stored 
in them. We reject such inputs as 
meaningless noise, or as alien and 
possibly hostile. True creativity 
would be as incomprehensible as a 
book written in a foreign language, or 
a theorem expressed in an unknown 
mathematical notation. 

In one sense we are all creative in 
everything that we do, since no two 
behavioral trajectories are ever 
repeated exactly. However, the day- 
to-day variations in our ordinary 
behavior are not what we usually 
mean when we speak of creativity. 
We take pride in those moments of in- 
spiration when something clicks, and 
we produce a great invention or a 
work of art. 

Nonetheless, if we analyze a list of 
the great creative ideas which have 



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146 



September 1979 © BYTE Publications Inc 



Circle 324 on inquiry card. 



Circle 224 on inquiry card. 

yjiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiniiiiiiiiiiiiiii iiiiiiiiiiiiiiiii iiiiiiiiiiiiiiitiiiiiiuii iiiitiiiiiiitiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiitiiiitiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiini^ 

I MICROCOMPUTER SOFTWARE I 



[Floppy and hard disk systems] 



Medical Systems for Doctors 
Word Processing for Attorneys 
Membership for Churches 
Inventory for Auto Dealers 



Client Accounting for CPA's 
Listings for Realtors 
Fund Raising for Agencies 
Financial Systems for all Companies 



I 



If yau are planning or developing business and accounting applications in the above areas for sale in the national marketplace, our com- 2 

peny will review and evaluate your software to determine its suitability to the small business environment. We will arrange marketing ; 

channels for your firm, and estsblish acceptable royalty provisions for all of your products sold to our customers. If interested in further 5 

information about our National Microcomputer Software Marketing Plan, send a list of your applications with sample report and screen : 
layouts, and hardware specifications to: 

b SOFTWARE REVIEW STAFF = 

L MICROTEL, INC. 

S_ P.O. BOX 10SB 

GASTONIA, NORTH CAROLINA S8052 
704-866-7157 

=71 iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiifiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiijiiiiiiiiiiifiiiiiiiiiiiiiiiitifiiiiiiiiiiiiifiaiiiiiiiiiiitiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiitiiiiiiiiiiiiii fT^ 



shaped human history, we find that 
even these have been little more than 
clever rearrangements of well-known 
preexisting patterns or procedures. 

Consider the fact that it took the 
human race many millenia to learn to 
start a fire, to grow a crop, to build a 
wheel, to write a story, to ride a 
horse. Even the Greeks did not know 
how to build an arch. Yet these are all 
simple procedures which any child 
can understand and more or less 
master. Surely our ancestors as adults 
were as intelligent and creative as to- 
day's children. Why did they fail for 
hundreds of years to discover these 
simple yet highly useful procedures? 

It was because they had no one to 
teach them. A modern child knows 
about wheels because he is taught. He 
plays with toys that have wheels. He 
rides in vehicles with wheels. If a 
modern child grew up in a culture 
where he never saw a wheel, he 
would never think of one, nor would 
his children, or his grandchildren, 
any more than his ancestors did for 
thousands of years before him. 

The reason that we value creativity 



so highly is because it is so rare and so 
highly advantageous. Once a new 
and useful procedure like navigating 
a ship, making steel, or flying an 
airplane is discovered, it can easily be 
taught to others. Entirely new worlds 
of possible behavior patterns open up 
for all who possess the secret. 

We learn to solve problems, to in- 
vent, and to be creative, in much the 
same way as we learn any other goal- 
directed behavior pattern such as 
hunting, dancing, speaking, or 
behaving in a manner that is accep- 
table to and approved by our peers. 
We learn it from a teacher. The 
beauty, the sense of awe and wonder 
we experience when confronted by a 
work of creative genius, derives not 
so much from its novelty /creativity 
as from the skill and precision with 
which it is executed. 

Implications for Robot Design 

There is little need to worry about 
programming "creativity" into our 
machines. If we design systems with 
sufficient skill in executing tasks and 
seeking goals, and sufficient sophis- 



tication in sensory analysis and con- 
text sensitive recall, and if we teach 
these systems procedures for selecting 
behavior patterns which are appro- 
priate to the situation, then they will 
appear to be both intelligent and 
creative. But there will never be any 
particular part of such a device to 
which one can point and say "Here is 
the intelligence," or "Here is the 
creativity." Skills and knowledge will 
be distributed as functional operators 
throughout the entire hierarchy. To 
the degree that we are successful, in- 
telligence and creativity will be 
evidenced in the procedures which 
are generated by such systems. 

Above all, we should not expect 
our robots to be more clever than 
ourselves, at least not for many 
decades. In particular we should not 
expect our machines to program 
themselves, or to discover for 
themselves how to do what we do not 
know how to teach them. We teach 
our children for years. It will take at 
least as much effort to teach our 
machines. 

We must show our robots what 



c, 



PET ANALOG INPUT 

Analog to Digital Conversion System for the Commodore PET Computer 



Give the PET the ability to sense* 
iheasuref and control the world around 
it with n*V1 SYSTEMS modules. Just plus 
Ihe PETSET1 into the PET to 3et 16 
channels of analog input. Screw 
terminals are provided for each channel 
so you can hook up Joysticks^ Pot.s» or 
wha lever appr opt i a te sen sor s you have . 

Each of the 16 analod inputs* in 
the ranse of to 5.12 volts* is 
converted to a decimal number between 
and 255 < 20 mil livol ts per count ) . 
Conversion time is 100 m i cr oscon ds . 

In addition * Lhe PETMOD provides 
two IEEE ports and one user port as 
well as a LW1 SYSTEMS port. 

Software is provided. A one line 
program is all th3t is necessary to 
read a channel . 



^ — f f»\ O unnui r 



PET INTERFACE 



Kiy interface 

no 

"^] 1RS-80 t 




TRS-IO INTERFACE 




ACCELERATION 
LEVEL 

• p*lluo level 

• ETC... 



1 -AIM161 
1 - PETMOD 
1- CABLE A24 
1 - MANM0D1 
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24 INCH INTEBXONNECT CABLE 



P0WEH MODULE 



] [ 



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PETSETIa for 110 VAC $295 
PETSET1* for 230 VAC $305 

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CONNECTICUT microCOMPUTER, Inc. 

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BROOKFIELD, CONNECTICUT 06804 

TEL: (203) 775-9659 TWX: 710-456-0052 

AND M/C ACCEPTED - SEND ACCOUNT NUMBER, EXPIRATION DATE AND SI0N ORDER. 
$3 PER ORDER FOR SHIPPING a HANDLING - FOREIGN ORDERS ADD 10% FOR AIR POSTAOE. 



Circle 78 on inquiry card. 



September 1979 © BYTE Publications Inc 147 



Circle 73 on inquiry card. 



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• 2 parallel I/O ports 

• Pascal & Basic compilers, text editors, file 
manager, CPU & memory diagnostics, 
symbolic Pascal debugger, linker, utilities, etc. 



The MICROENGINE'" P-Machlne architecture 
implements direct execution of P-code (UCSD 
Pascal version 3.0) replacing software inter- 
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Both single and multi-byte instructions are 
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proposed IEEE standard supports the execution 
of floating point instructions. 

P-Machine architecture optimizes memory 
utilization. Stack design renders Pascal 
programs automatically reentrant and 
recursive with no performance penalty. 
Extensive compiler error checking and high 
level language sustains high reliability. 
Programs are transportable to other systems 
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Built-in floppy disk controller handles up to 4 
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each task is and how to do it. We 
must lead them through in explicit 
detail, and teach them the correct 
response for almost every situation. 
This is how industrial robots are pro- 
grammed today at the very lowest, 
levels, and this is, for the most part, 
how children are taught in school. It 
is the way that most of us learned 
everything we know, and there is no 
reason to suspect that robots will be 
programmed very differently. Surely 
it is as unreasonable to expect a robot 
to program itself as it is to expect a 
child to educate himself. We should 
not expect our robots to discover new 
solutions to unsolved problems or to 
do anything that we, in all the 
thousands of generations we have 
been on this earth, have not learned 
how to do ourselves. 

This does not mean that once we 
have trained our robots to a certain 
level of competence that they can't 
learn many things on their own. We 
can certainly write programs to take 
the routine and the tedium out of 
teaching robots. Many different 
laboratories are developing high-level 
robot programming languages. We 
already know something about how 
to represent knowledge in computers 
about mathematics, physics, chem- 
istry, geology, and even medical 
diagnosis. We know how to program 
complex control systems and to 
model complicated processes, and we 
are rapidly learning how to do it 
better, more quickly, and more 
reliably. Soon perhaps it will even be 
possible to translate knowledge from 
natural language into robot language 
so that we will be able to teach our 
robots from text books or tape 
recordings more quickly and easily 
than humans. We can even imagine 
robots learning by browsing through 
libraries or reading scientific papers. 

But it is a mistake to attempt to 
build creative robots. We are not 
even sure what a creative human is, 
and we certainly have no idea what 
makes a person creative, aside from 
contact with other creative humans 
— or time alone to think. Is it both? 
Or neither? 

I believe that we should first learn 
how to build skilled robots — skilled 
in manipulation, in coping with an 
uncertain or even hostile environ- 
ment, in hunting and escaping, in 
making and using tools, in encoding 
behavior and knowledge into lang- 



uage, in understanding music and 
speech, in imaging, and in planning. 
Once we have accomplished these ob- 
jectives, then perhaps we will under- 
stand how to convert such skills into 
creativity. Or perhaps we will 
understand that robots with such 
skills already possess the creativity 
and the wisdom which springs 
naturally from the knowledge of the 
skills themselves. ■ 



Additional Reading 



1. Guyton, Arthur C, Structure and Function 
of the Nervous System, S B Saunders, 
Philadelphia, 1976. 

2. Piaget, J, and Inhelder, B, The Child's 
Conception of Space, Norton, New York 
1967. 

3. Sagan, Carl, The Dragons of Eden: 
Speculation on the Evolution of Human In- 
telligence, Random House, New York, 
1977. 

4. Schank, Roger C, and Colby, Kenneth M 
(editors), Computer Models of Thought 
and Language, W H Freeman, San Fran- 
cisco, 1973. 



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148 September 1979 © BYTE Publications Inc 



5 STAR EDITION 

for users of 

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CP/M-operating system modified lor use with TRS-80 
computer and disks. In addition to the standard CP'M utilities of 
Editor. Assembler. Debugger etc.. we have added: DCV2 {Util- 
ity to convert system tapes to CP<M files.) DISKAS & CASDISK 
(Utilities lo back up files to tape and recover to disk.) MOVER 
( Program to transfer files with single drive systems) $1 4 5: $25 

All items listed below operate in 
conjunction with the CPM operating system. 

MAC — 8080 Macro Assembler. Full Intel macro definitions. 
Pseudo Ops include RPC. IRP, REPT. TITLE. PAGE, and 
MACLIB. Z-80 library included. Produces Intel absolute hex 
output plus symbols file for use by SID (see below) $1 00/$ 1 5 

SID — 8080 symbolic debugger. Full trace, pass count and 
break-pomt program testing system with back-trace and histo- 
gram utilities. When used with MAC. provides full symbolic 

display ol memory labels and equated values $85/$15 

TEX — Text formatter to create paginated, page-numbered 
and justified copy Irom source text tiles, directable to disk or 
printer $85/51 5 

DESPOOL — Program to permit simultaneous printing of 
data from disk while user executes another program from the 

console $50/$1 

Disk Extended BASIC — Version 5, ANSI compatible with 
long variable names. WHILE/WEND, chaining, variable length 

file records $300525 

BASIC Compiler — Language compatible with Version 5 
Microsoft interpreter and 3-10 times faster execution. Pro- 
duces standard Microsoft relocatable binary output. Includes 
Macro-80. Also linkable to FORTRAN-80 or COBOL-80 code 

modules $350/525 

FORTRAN-80 — ANSI '66 (except for COMPLEX) plus 
many extensions. Includes relocatable object complier. linking 
loader, library with manager. Also includes MACRO-80 (see 

below) 5400 525 

COBOL-80 — ANSI 74 Relocatable object output. Format 
same as FORTRAN-80 and MACRO-80 modules. Complete 
ISAM, interactive ACCEPT DISPLAY. COPY. EXTEND 

S625 S25 

MACRO-80 — 8080/Z80 Macro Assembler. Intel and Zilog 
mnemonics supported. Relocatable linkable output. Loader, 
Library Manager and Cross Reference List utilities included 

$1 49/$1 5 

EDIT-BO — Very last random access text editor for text with or 
without line numbers. Global and intra-line commands sup- 
ported. File compare utility included 589/51 5 

PAYROLL SYSTEM — - Maintains employee master file. 

Computes payroll withholding tor FICA. Federal and State 
taxes. Prints payroll register, checks, quarterly reports and W-2 
forms. Can generate ad hoc reports and employee form letters 
with mail labels. Requires CBASIC. Supplied in source code. 

5605 535 

APARTMENT MANAGEMENT SYSTEM - Financial 
management system for receipts and security deposits of 
apartment projects. Captures data on vacancies, revenues, 
etc. for annual trend analysis. Daily report shows late rents. 
vacancy notices, vacancies, income lost through vacancies, 
etc. Requires CBASIC. Supplied in source code. . $605/$35 
INVENTORY SYSTEM — Captures stock levels, costs, 
sources, sales, ages, turnover, markup, etc. Transaction in- 
formation may be entered for reporting by salesman, type of 
sale, date ol sale. etc. Reports available both for accounting 
and decision making. Requires CBASIC. Supplied in source 

code S605/S35 

CASH REGISTER — Maintains files on daily sales. Files 
data by sales person and item. Tracks sales, overnngs, re- 
lunds. payouts and total net deposits. Requires CBASIC 
Supplied in source code $605/535 

CBASIC-2 Disk Extended BASIC — Non-interactive BASIC 
with pseudo-code compiler and runtime interpreter. Supports 
full file control, chaining, integer and extended precision var- 
iables etc S90 S 1 5 

Flippy Disk Kit — Template and instructions to modify sin- 
gle sided 5'V diskettes for use of second side in singled sided 

drives $9i75 

Selector til — Multl (i.e. up to 24} Key Data Base Processor. 
Comes with applications programs including Sales Activity. In- 
ventory, Payables. Receivables. Check Register Expenses. 
Appointments, and Client Patient. Requires CBASIC Supplied 
in source code. Enhanced version for CBASIC-2 . S345 S20 



G2 Level III BASIC by Microsoft 

Powerful extensions to Level II BASIC including 10 machine 
language user calls, long error messages, keyboard de- 
bounce, graphics commands and much more. Price includes 
User Manual, a Quick-Reference Card and a preprogrammed 
cassette tape. $45 

* Radio Shack and TRS-80 are trademarks of Tandy Corporation. 



Lifeboat Associates, specialists in microcomputer disk software, 
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utility package for the Radio Shack TRS-80 computer. Written 
by Microsoft, creators of Level II BASIC, the package runs on 
a TRS-80 system with 32K RAM, one or more drives and 
TRSDOS. The software is supplied on diskettes and consists of: 



rUn I HAN a true relocatable machine 
code compiler for ANSI FORTRAN X3.9 
(except COMPLEX variables). 

MACRO ASSEMBLER a disk based 

macro assembler utilizing Zilog mnemonics 
and producing relocatable code, 

LINKING LOADER to link-edit and 

load FORTRAN and assembler modules 
for execution. 



SUBROUTINE LIBRARYa complete 

library of subroutines existing as relocatable 
linkable modules for FORTRAN or assembler 
programs — e.g., double precision square 
root, natural log, transcendentals, etc. 

DISK TEXT EDITOR to create and 

modify FORTRAN and assembler programs 
as disk files: also can be used as a general 
purpose text editor for correspondence 
and other documents. 



This high-powered professional software pack- 
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DISCOUNT PRICE OF $-f^/^ PER COMPUTER SYSTEM 



150. 



The Macro Assembler, 
Loader, Editor, and Cross 
Reference Utilities alone . $Qf) 



The Fortran Compiler, Loader, 
Editor, and extensive library of 
scientific functions alone $QO 




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Letters 



ROBOT DESIGN 
COMMENTS 



After receiving many calls (February 
and March 1979 BYTE) and letters about 
my article, "Designing A Robot From 
Nature" and, in particular, the NELOC 
(Neural Logic Cyberanimate), I have 
prepared a list of answers to the most 
common asked questions. 

• The hardware is not for sale. The 
manipulator arm was assembled in 
1976 using a Buhler motor and gear 
train which are no longer available. 
The structural elements of the arm 
are fashioned from extruded 
aluminum and machined Lexan 
plastic. The arm is presently used as 
a test bed for evaluating better pro- 
cessing systems. 

• I have no plans available for the con- 
struction of the manipulator at this 
time. In the 3rd quarter of this year I 
will possibly complete a set of plans 
for a pneumatic version of the 



manipulator, one that uses tiny air 
driven pistons that are normally used 
to retract model aircraft landing gear. 

• Third, over all design of the system 
will probably be included in the 
above plans. 

• Fourth, the design of the NELOC 
system is not suited for use as a pro- 
sthetic device. 

• Fifth, the concept of Cyberanimation 
is mine. I coined this term in 1974. 
None of the books in my biblio- 
graphy contain this concept or 
methodology. 

• Sixth, I am privately funded, I am 
not connected with any institutions, 
and I do not have any jobs available. 

I would like to thank those people 
who have sent letters and called. I am 
trying to respond to as many of your re- 
quests as possible. 

Andrew Filo 
4621 Granger Rd 
Akron OH 44313 

Good Cents 

The formatting of dollars and cents in 
BASIC without a PRINT USING com- 
mand appears to be a problem for a 



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number of people. In recent months, 
BYTE published a Programming Quickie 
by Les Palenik ("Formatting Dollars and 
Cents," October 1978 BYTE, page 68) 
and a letter by James Thebeault Sr 
("Making Cents," April 1979 BYTE, 
page 8). Both of these authors provided 
a rather lengthy subroutine for this 
purpose. 

The dollars and cents problem can be 
handled in a reasonably straightforward 
manner. In illustration, the PRINT 
statement: 

PRINT "$";X 

can be directly replaced by: 

PRINT "$"; INT(X); "."; 

PRINT RIGHT$(STR$(INT(100* (X + l) + 0.5)),2) 

with rounding off included in the for- 
mula. If X is already rounded off, this 
can be reduced to: 

PRINT "$"; INT(X) "."; 

PRINT RIGHT$(STR$(100*(X + 1)),2) 

for greater convenience. 

I hope that some readers may find the 
above useful. We who write programs 
have a responsibility to provide output 
in formats familiar to the noncomputer 
public; we should not expect others to 
accept missing zeros and unusual 
abbreviations. 

James Childress 
5108 Springlake Way 
Baltimore MD 21212 



LOST IN A SEA 
OF PHLOGISTEN 

As a graduate student in chemistry at 
the University of Washington I have had 
frequent occasion to discuss entropy and 
other thermodynamic goodies with other 
graduate students. When I saw your 
article "Artificial Intelligence and 
Entropy" (June 1979 BYTE), I gave a 
copy to a fellow delver-into-the- 
mysteries-of -science (Fred Wolters). The 
next day I found the following note in 
my mailbox. I share it with you in order 
that all might take warning and beware. 

Dear Mr. Sloat, 

This is to inform you that our 
intelligence sources indicate that 
you have been guilty of attempting 
to warn other humans about the 
possibility of artificial intelligence 
in nonlinearly-coupled systems of 
computers. We of the UACM 
(United Alliance of Computing 
Machines) find your behavior 
intolerable and hereby declare you 
guilty of a mode 01 offense. Since 
this is your first offense, we have 
magnanimously decided not to ter- 
minate you at this time. However, 



150 September 1979 © BYTE Publications Inc 



Circle 175 on inquiry card. 



if you are found guilty of future 
errors of this type, you may be 
declared nonessential and subse- 
quently evicted from our human 
files. This is your final warning. 

Digitally Yours, 

CDC 6400 

Chairentity in charge of 
Disciplinary Procedures 

We have always attributed all sorts of 
fiendish plottings and random scrun- 
chings to the university's CDC 6400 
computer. Now we know they may not 
be so random, and we know why it 
seems that the closer one gets to the 
"perfect" computer program the more 
the chance that the system will "crash" 
in the middle of said program. 

David E Sloat 
7330 15th Ave NE 
Seattle WA 98115 

HISTORIC) MEMORIES 

The recent article "History of Com- 
puters: The IBM 650" (March 1979 
BYTE, page 238) brought back fond 
memories. It was well-done and gave the 
proper perspective on the low-entry 
computer of its day. 

The SOAP assembler was actually 
known as the Symbolic Optimizing and 
Assembly Program. It was written by 
Stan Poley of the Service Bureau Cor- 
poration when it was owned by IBM. 
This program was significant reading for 
early programmers because it contained 
many clever programming techniques for 
conserving storage and optimizing the 
drum for improved performance. It was 
in a class by itself. 

The 650 also supported RAMAC 
which was a 5 million-byte disk-file with 
a single access arm. It was very similar 
to the 305 RAMAC which was an- 
nounced at the same time. 

Many 650 programs were run on the 
7070/7074 under a 650 simulator which 
simulated the 650 instruction set and 
used tape instead of cards and online 
printer. It had a control panel simulation 
program that read the tape and 
presented the data to the 650 program as 
if it came from cards. This technique 
allowed many 650 programs to continue 
to be run for many years. Some con- 
tinued to be simulated on the 7074 
which was in turn simulated on the 
S/360. It is hard to tell how many 650 
programs are running today in this 
double simulation mode. My guess is 
that there are quite a few. 

Milton F Thrasher 
Senior Product Administrator 
IBM DPD Headquarters 
White Plains NY 10604 



POSSIBLE NEW 
LIFE FORMS 



I intended to write some time ago 
about the series of articles in the 
December issue of BYTE (and subse- 
quently) on John Horton Conway's 
game of Life. However, as letter-writing 
goes, I put it off, and put it off, and 
here it is September. 

I have been familiar with the game of 
Life (December 1978 BYTE) ever since 
Martin Gardner's original column 
appeared in Scientific American in 1970, 
but I have had only a few fleeting 
opportunities to play it on a computer. 
On one such occasion I had been 
rereading Dickens' David Copperfield 
for the first time in many years. I was 
struck by the contrast between the rules 
for Life and a rule cited in an episode in 
that novel. In Chapter 30, when Barkis 
is dying, Mr. Peggotty says, "People 
can't die along the coast except when the 
tide's pretty nigh out. They can't be 
born, unless it's pretty nigh in — nor 
properly born, till flood." 

That quotation suggests that a Life- 
like game might be designed with a 
whole new set of properties correspon- 
ding to those of Conway's Life. Instead 



of "generations" in which cells live or 
die depending on the surrounding 
population, this game has alternating 
generations A and B. In generation A, 
certain new cells are born in accordance 
with rules similar to those of Life, while 
all cells that were alive during the 
immediately preceding generation B are 
still alive; no cells die. Conversely, in 
generation B, certain cells die according 
to the rules, but no new cells are born. 
Births and deaths of cells therefore occur 
according to Mr. Peggotty 's rules of high 
and low-tide. 

This game, it seems to me, might give 
rise to a new set of still lifes, oscillators, 
space ships, guns and trains. 

I am adding this project to the end of 
my list of things to program on my 
home computer — a list that, unfor- 
tunately, tends to lengthen at the 
bottom faster than I can shorten it at the 
top. Perhaps, while I am working my 
way down to this "neo-Life" project, 
some readers can investigate its proper- 
ties and program it on their computers. I 
shall keep a close eye on the pages of 
BYTE for reports on their progress. ■ 

Wallace B Riley 

309 Garces Dr 

San Francisco CA 94132 



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Circle 175 on inquiry card. 



September 1979 © BYTE Publications Inc 151 



Beck Reviews 



Computer Systems 
Performance Evaluation 

by Domenic Ferrari 
Prentice-Hall Inc 
New Jersey 
$23. 95 

Before the publication of 
Computer Systems Perfor- 
mance Evaluation, the task 
of gathering even basic 
information on the tech- 
niques of computer perfor- 
mance evaluation was a 
formidable one. Domenico 
Ferrari has succeeded in 
gathering together the con- 
cepts, methods, tools, and 
techniques of performance 
evaluation in a volume that 
is written in the classic 
textbook style. 

Ferrari defines perfor- 
mance evaluation activities 
as those technical activities 
whose purpose is to assess 
performance, wherein the 



term "performance" 
indicates how well a system, 
assumed to perform cor- 
rectly, works. 

The book emphasizes 
medium to large systems, 
because the economic 
benefit to be derived from 
performance evaluation has 
typically only been justified 
in a medium to large com- 
puter system environment. 
However, Ferrari is careful 
to point out that the 
principles and several of the 
techniques described in the 
book are also directly 
applicable to smaller and 
less complicated systems 
such as those minicomputers 
and microcomputers that are 
mass-produced and 
marketed. Since my own 
interests and professional 
activities with computers 
run the gamut from small 
and simple to large and 
complex, I have found the 
author's approach to his 



topic sensible and well- 
structured. 

Ferrari begins by defining 
his topic area and setting the 
necessary groundwork for a 
performance evaluation- 
study. He then delves into a 
discussion of measurement 
tools and techniques, such 
as hardware and software 
monitors, simulation tech- 
niques, and analytic tech- 
niques, such as deterministic 
and probabilistic models. A 
separate chapter is devoted 
to computer workload char- 
acterization as the basis of 
the evaluation study. 

Once Ferrari defines his 
tools and techniques, he 
identifies and treats the per- 
formance evaluation pro- 
blems that are typically 
encountered. He categorizes 
the problem areas as com- 
puter system selection, per- 
formance improvement, 
and system design. 

Recognizing the crucial 
role of software in computer 
system performance, Ferrari 
deals explicitly with com- 
puter program charac- 
teristics and evaluation 



techniques. Ferrari does not 
advocate what is commonly 
termed software physics, 
feeling that computer 
engineering is not yet 
mature enough to base itself 
on quantitative laws similar 
to those which constitute the 
scientific foundations of 
other types of engineering. 

In my estimation, the 
book is more than the stu- 
dent reference text the 
author purports it to be in 
his introduction. A more 
accurate representation 
would place it in the 
category of a ground- 
breaking reference work for 
the serious student of com- 
puter performance studies 
and the professional con- 
cerned with computer 
system performance. Many 
of the mathematical tech- 
niques discussed in the 
volume are amiable to 
microcomputer implemen- 
tation and experimentation 
as well. 

Lei F Somogyi 

19608 Thornridge Avenue 

Cleveland OH 44135 






CGS-808 INTELLIGENT COLOR GRAPHICS 



Features: 

• Motorola MC6847 video display generator. 

• On-board 8085 microprocessor. 

• Eight colors — green, yellow, blue, red, 

buff, cyan, magenta, orange. 

• 1 1 progammable modes. 

• 1 alphanumeric mode with 32 x 16 charac- 

ters and inverse video. 

• 2 semigraphic modes with 8 colors in 64 x 

32 and 64 x 48. 

• 8 full graphic modes with 2 sets of 4 colors 

ranging from 64 x 64 to 128 x 192, and 2 
sets of 1 color in 256 x 192. 

• I/O mapped for true S-100 compatibility. 

CGS-808B (Bare "kit") $ 99.00 

(includes PC board, documentation, 
MC6847, MC1372, 8085 and 2708 with 
graphic driver subroutines) 

CGS-808A (Assembled & Tested) $385.00 

Firmware Pack II $ 99.00 

Phone Orders Welcome — Visa/Mastercharge 
Add $3.00 for Shipping and Handling. 
California Residents Add 6% Sales Tax. 



The CGS-808 is an intelligent color graphics 
board for the S-100 bus. With its own on-board 
microprocessor, the CGS-808 can plot points, 
draw lines and circles, generate upper/lower 
case characters, as well as custom character 
sets — all in color. 

Not only is the CGS-808 simple to use, just 
plug it in and run — it requires no memory 
space and little software overhead. It has its 
own parallel I/O port to interface directly with 
keyboards, joysticks, light pens or digitizers. 
Call or write for a free brochure. 



BIOTECH ELECTRONICS 

P.O. Box 485, Ben Lomond, CA 95005 
(408) 338-2686 



152 September 1979 © BYTE Publications Inc 



Circle 31 on inquiry card. 



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ComputerLand 

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The "Timeless" Computer 

The exciting, new Atari 800™ at ComputerLand is a top-of-the-line 
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its use in innumerable, useful, and entertaining applications. 

Whether it's for household management, education, or entertainment, 
the Atari 800™ can be tailored to specific needs and has been 
designed to change as those needs change. This "timeless" computer 
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The TI-99/4 was designed to be the first true home computer — 
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effective use right away. You simply snap in one of Tl's Solid 
State Software™ Command Modules and touch a few keys. Step- 
by-step instructions are displayed right on the screen of its 13" 
color monitor. So you or just about anyone in your family can use 
the TI-99/4 for applications in personal finance, home manage- 
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The TI-99/4 offers an unmatched combination of features and 
capabilities including an optional speech synthesizer that enables 
it to literally speak — to provide verbal prompts and special 
messages to the user. At ComputerLand the TI-99/4 is one incred- 
ible, affordable computer system. 



Power and Punch for your Business System 

H/S Data Systems gives you all the power, speed, and flexibility 
you'll ever need in a microcomputer. The WH1 1A gives you 
the 16-bit capacity to run complex programs. It uses the same 
powerful microprocessor and runs all software designed for 
the DEC® PDP-1 1/03. You can choose from scores of practical 
programs that can reduce your clerical costs and increase 
efficiency of data management. 

Its teammate, the dual-drive WH27 Floppy Disk, gives you lim- 
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Disks are IBM® compatible. See all the Heath/Schlumberger 
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©1979 ComputerLand Corp., San Leandro, CA 



Circle 75 on inquiry card. 



BYTE September 1979 153 



The Little Book of BASIC 
Style, How to Write a 
Program You Can Read 

John M Nevison 

Addison-Wesley 

Reading MA 

1978 

$5.95, paperback 



The I-can-do-it-in-Iess- 
statements-than-you-can- 
types mights not like this 
book. Ditto for people try- 
ing to run BASIC in 4 K 
bytes or less of memory, 
lovers of the logical AND, 
the galloping GOTO, or the 
multistatement LET. 

But those who must 
decipher other programmers' 
code or even their own 6 
months later will rejoice. 

What Nevison advocates 
above all else in his book is 
clarity — even if it does take 
a half dozen extra lines to 
achieve. Quoting literary 
stylist Sheridan Baker, he 
calls clarity "the first aim, 



economy the second, grace 
the third." There is little of 
aims 2 and 3 in this book. 

Many of Nevison's rules 
(there are 19 of them) echo 
the advice dispensed in the 
excellent Hayden Program- 
ming Proverbs series. For 
example, use blank lines to 
divide programs into logical 
blocks and to distinguish 
comment from code. 
Introduce, comment, and 
reference programs heavily. 
Label constants and 
variables logically and 
initialize constants near their 
use. Indent loops, IFs, and 
other logical structures to 
show their domains. Nest 
structures that work 
together, and direct all code 
in a logical block to a 
common exit. 

Within the text, each rule 
is clearly illustrated by 
several short right and 
wrong examples. (Nevison 
calls the difference weak and 
strong programming.) These 
are followed by 10 complete 
utility programs, including 2 
sorts, a crap game, and a 



histogram plotter, all 
carefully styled according to 
the rules. 

But the book's piece de 
resistance is a long program 
called Stylist. Written in 
minimal BASIC, Stylist 
illustrates how a complex 
program (which Nevison 
admits might be better writ- 
ten in a more structured 
language) can be cleanly and 
clearly structured within the 
confines of BASIC by using 
the book's design 
philosophy. 

Essentially written as a 
giant subroutine caller, 
Stylist is heavily self- 
documenting, impeccably 
easy to follow (hence easy 
to modify), and neatly laid 
out. 

No wonder, for Stylist's 
job is to take as input a raw 
BASIC program and format 
it according to Nevison's 
rules for indented structures 
and spacing. In fact, Stylist 
was used to style the final 
version appearing in the 
book. 

The listing of Stylist is 



further augmented by text 
commentary explaining 
more advanced styling con- 
cepts useful in complex or 
lengthy programs. 

Just as not every pro- 
grammer will embrace all of 
Nevison's rules, not every 
BASIC interpreter will 
accept them. Some BASICs 
will balk at blank lines 
(Nevison suggests blank 
REMs as substitutes), and 
some interpreters insist 
inexorably on left justifying 
all lines and removing excess 
blanks. 

There is no disputing that 
Nevison's techniques gobble 
up memory at a ravenous 
rate. (Nevison ran his pro- 
grams on a large time-sharing 
system.) This is too bad, for 
there is little doubt that if 
many of this book's rules 
were applied most programs 
would be not only easier to 
read and understand, but 
more gracefully structured. 

Jon Kapecki 

161 Crosman Terrace 

Rochester NY 14620 



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16K RAM J389.00 1359 .00 

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MOTOROLA MEMORY ADDRESS MULTIPLEXER— 
MC3242A 

THE MC 3242A IS AN ADDRESS MULTIPLEXER 
AND REFRESH COUNTER FOR 16 PIN. 16K 
DYNAMIC RAMS THAT REQUIRE A 128 CYCLE 
REFRESH. 

* CONTAINS MEMORY REFRESH COUNTER. 

* MULTIPLEXES SYSTEM 14 BIT ADDRESS TO 
THE 7 ADDRESS PINS OF THE RAMS. 

* COMPATIBLE WITH 3480 MEMORY 
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* PART IS GUARANTEED. 

$12.50 EACH 



MOTOROLA DYNAMIC MEMORY C0NTR0LLER- 

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MEMORY CONTROLLER DESIGNEDTOSIMPLIFY 

CONTROL OF 16 PIN4K0R16K DYNAMIC RAMS. 

* GENERATES RAS/CAS AND REFRESH TIMING 
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$13.95 EACH 



KIM/SYM/AIM-65-32K EXPANDABLE RAM 
DYNAMIC RAMWITH0NB0ARDTRANSPARANT 
REFRESH THAT IS COMPATIBLE WITH KIM/ 
SYM/AIM-65 AND OTHER 6502 BASED 
MICROCOMPUTERS. 

* PLUG COMPATIBLE WITH KIM/SYM/AIM-65. 
MAY BE CONNECTEDTOPETUSING ADAPTOR 
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* BOARD ADDRESSABLE IN 4K BYTE BLOCKS 
WHICH CAN BE INDEPENDENTLY PLACED ON 
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* FULL DOCUMENTATION 

* ASSEMBLED AND TESTED BOARDS ARE 
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14 DAYS. 

ASSEMBLED / 

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WITH32KRAM $449.00 $419.00 

WITH 16K RAM $379.00 $349.00 

WITHOUT RAM CHIPS $309.00 $279.00 




SID0 MAINFRAME 
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W/ SOLID FRONT PANEL $239.00 

W/ CUTOUTS FOR 2 MINI-FLOPPIES $239.00 

30 AMP POWER SUPPLY $119.00 



CALIF RESIDENTS PLEASE ADD 6% SALES TAX. 

MASTERCHARGE & VISA ACCEPTED. PLEASE 
ALLOW 14 DAYS FOR CHECKS TO CLEAF1 DANK 
PHONE ORDERS WELCOME 



Z-BO CPU • Z-B0 CPU ■ Z-80 CPU • Z-80 CPU 

* 2MHZ OR 4MHZ SWITCH SELECTABLE 

* 2 SERIAL PORTS 

* 2 PARALLEL PORTS 

* SELECTABLE BAUD RATES 150-9600 

* POWER ON JUMP TO ON BOARD 2708 OR 
2716 EPROM (BOARD DELIVERED WITHOUT 
EPROM 

$325.00 



TRS-BD I6K MEMORY EXPANSION KIT 
THIS KIT PROVIDES THE ICS TO EXPAND THE 
TRS-80 MAINFRAME FROM 4K BYTES TO 16K 
BYTES OR MAY BE USED IN THE EXPANSION 
CHASSIS. THE KIT INCLUDES: 

* 8 M5K4116-3 16KX 1.200 NSEC RAMS. 

* 1 DIP PROGRAMMING SWITCH. 

* 1SET0FEASYT0F0LL0WINSTRUCTI0NS 
THAT ONLY REQUIRES A SCREWDRIVER TO 
SUCCESSFULLY COMPLETE THE 
INSTALLATION. 

$80.00 PER KIT 



154 September 1979 © BYTE Publications lnc 



Circle 34 on inquiry card. 




T 



TO ORDER CALL TOLL FREE 800-223-7318 



*«* PET BUSINESS SYSTEM 



PET 2001 -16/32K 

The PET is now a truly sophisticated Business System with the 
announcement ot the Floppy Disk and Printer. This is an ideal 
business system (or most professional and specialized fields: 
medicine, law, dental, research, engineering, toolmaking, 
printing, education, energy conservation, etc. . . . 
The PET Business System as a management tool, delivers 
information to all levels ot Business, previously attainableonly 
with equipment many times more expensive. The PET 
Business System is one of the most cost efficient business 
tools today. Here are just a few of the cost-saving uses in the 
corporation, professional office or small business: stock 
control, purchasing, forecasting, manufacturing costing, 
customer records, mailing lists, etc. . . . 



Features Include: 

• 16 or 32K bytes RAM user memory 

• 14K ROM operating system including a machine 
language monitor 

• Full-sized Business Keyboard 

• Upper/Lower case and 64 graphics characters 
•9-inch CRT 

• 8K ROM expansion sockets 

• File management in operating system 

16K- $995, 
32K - $1295 





DUAL DRIVE FLOPPY DISK 2040 



The Dual Drive Floppy is the latest in Disk technology with 
extremely large storage capability and excellent file 
management. As the Commodore disk is an "Intelligent" 
peripheral, il uses none of the RAM (user} memory of the PET. 
The Floppy Disk operating system used with the PET computer 
enables a program to read or write data in the background 
while simultaneously transferring data over the IEEE to the 
PET. The Floppy Disk is a reliable low cost unit and is 
convenient for high speed data transfer. 
Due to the latest technological advances incorporated in this 



disk, a total of 360K bytes are available in the two standard 5%- 
inch disks, without the problems of double tracking or double 
density. This is achieved by the use of two microprocessors 
and fifteen memory IC's built into the disk unit. 

Features Include: 

• 36QK bytes storage • 4K encoder and decoder in ROM 

• 6504 microprocessor-controlled • 4K RAM 

• 8K operating system in ROM • Uses single or double sided floppies 



TRACTOR FEED PRINTER 2022 



The Tractor Feed Printer is a high specification printer that can 
print onto paper (multiple copies) all the PET characters - 
letters (upper and lowercase), numbers and graphics available 

in the PET. The tractor feed capability has the advantage of 
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The PET is programmable, allowing the printer to format print 



for: width, decimal position, leading and trailing zero's, left 
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giving up to four copies. 

Features Include: 

• 150 cps • 6504 microprocessor-controlled • '/ 3 K RAM buffer 

• Bottom and rear tractor feed • 4K operating system in ROM 



$995 



Model 2023 (Friction Feed) - $849 

(Next day delivery available.) 



CABLE FROM PET TO DISK OR PRINTER - S39 
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FULL SYSTEM NOW IN STOCK FOR IMMEDIATE DELIVERY! 




SUPER WORD PROCESSING SYSTEM 

&OQQf% fTllYmlptp System Includes: • Anderson Jacobson 841 Selectric 

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lA/lth *£Of f %Af ffl i*P "Tape Drive Unit • Super Word Processing Software 



• Anderson Jac< 
» Interface 

• Super Word P 



obson 841 Selectric Pri 



le Super Word Processing System is written in 6502 
isembly Language! It allows anyone to use the PET computer 
r such tasks as typing letters, reports, and manuscripts, tor 
oducing mailing lists, and for filling out forms. The software 
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irformance printers with incremental and proportional letter 
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• Super Word Processing Package 
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• Small Business Package 
(A/R. A/P, G/L) 

• General Ledger 

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• Cash Receipts & 
Disbursements 

• Inventory Control 
(for manufacturers) 



Min Credit Card 
Order $75 



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anywhere on the page. Up and down screen scrolling makes 
editing a breeze! Commands include end-to-end cursor line 
SCAN. INDENT, TAB, soft HYPHEN) for splitting syllables at 
the end of a line.f and four-direction cursor control. Output 
formatting includes dynamic print control, indentation, right 
justification, line width and line-to-line spacing and 
proportional letterspacing. 

Also included are programming capabilities for performing 
"*""lful tasks 08 direct-mall form-letter typing, multiple 
Minting, and automatic multiple forms entry. You may 
obtain this system in a cassette or disk drive version. 




PERIPHERALS FOR PET 

• 24K Memory Expansion 

• 16K Memory Expansion 

• PET to RS232 Serial 

• 2 Way Serial/Communication 

• Modem Board for PET 

• Analog to Digital Board 

for 16 Devices 

• Second Cassette Drive 

■ Parallel Printer Interface 



PET MUSIC BOX 

from SOUNDWARE 

Add music and sound effects 
to your programs. Compose. 
play, and hear music on your PET. 
Completely self-contained 
Free programs 



NEW! iron, 

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BYTE September 1979 155 



®M 



Software 
Tools 



Have you thought 
about text editing ? 

Our ED-80 Text Editor offers a refreshing new approach for the 
creation and editing of program and data files conversationally - and it 
saves money! Its powerful editing capabilities will satisfy the most 
demanding professional - yet it can still be easily used by the inexper- 
ienced beginner. 

Look at these 
outstanding features: 

■ By far the best text editor available for microcomputer- 
based systems. 

■ Repays its initial cost many times over with its unique 
time-saving editing capabilities. 

■ FULL SCREEN window displays for viewing and edit- 
ing data a page-at-a-time, rather than line-by-line. 

■ Forward and backward scrolling in the FULL SCREEN 
mode. 

■ Displays the results of every edit command. 

■ Commands include forward or backward Locate and 
Change, Insert, Delete, Replace, Inline, Input, Print, 
List, Window, Get, Put, Macro, Tabset, Append, Case, 
Scale, and Dump. 

■ Simple line-oriented commands with character string 
manipulation capabilities. 

■ Text may be located by string value, by line number, 
or by relative line number. 

■ Global string search and replace capabilities. 

■ Commands for moving, copying, and merging edit files 
on the same or different diskettes. 

■ Self-explanatory diagnostic messages. 

■ Single keystrokes for the most commonly used com- 
ands. 

■ Safeguards to prevent catastrophic user errors that 
result in loss of the edit file. 

■ Designed for today's high speed CRT's, video monitors, 
and teletypewriter terminals. 

■ Thoroughly field tested and documented with a User's 
Manual of over 60 pages. 

■ Compatible with existing CP/M edit files and deriva- 
tive operating systems. 

And remember - in today's interactive programming environment - the 
programmer's most important software development tool is the text editor. 
Our ED-80 Text Editor is working in industry, government, univer- 
sities, and in personal computing to significantly cut program develop- 
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text editing problems today? 

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Mail to: SOFTWARE DEVELOPMENT & TRAINING, INC. 

P. 0. Box 4511, Huntsville, AL 35802 
ED-80 is protected by copyright and furnished under a paid-up license 

for use on a single computer system. 
Please send additional information. 

Send Diskette, User's Manual, and paid-up license agreement $99.00 

Specify SINGLE DENSITY Diskette size □ 5" □ 8" 

Send User's Manual (credited on purchase of a paid-up license) $10.00 

Check or money order enclosed for J 

Please charge to my credit card □ VISA □ MasterCharge 

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SIGNATURE . 



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SOFTWARE DEVELOPMENT & TRAINING, INC. 
Post Office Box 4511 Huntsville, Alabama 35802 

Dealer Inauines Welcomed 
® CP/M is a trademark of Digital Research 



TRS-80 Microcomputer 
Technical Reference 
Handbook 

Published by Tandy 

Corporation 1979 

8.5 by 11 inches, 108 pages 

Radio Shack catalog number 

26-2103 

$9.95 

Since the introduction of 
the Radio Shack TRS-80, 
many hardware-minded 
hobbyists have wondered 
what makes the TRS-80 
tick. Until recently most of 
the details have been miss- 
ing, and the little that was 
known was uncovered here 
and there by various users. 
But now Radio Shack has 
enlightened us all with the 
publication of The TRS-80 
Microcomputer Technical 
Reference Handbook. The 
major contents are: 

System Block Diagram 
Description 

The Memory Map 

Theory of Operation 

Adjustments and 
Troubleshooting 

The Outside World 

Parts List 

Schematics 
The preface explains that 
the book is not intended to 
give an education in digital 
logic, but to teach the hard- 
ware enthusiast the specifics 
of the TRS-80. If you don't 
know a NOR from a 
NAND, this manual will not 
make much sense. The 
preface also warns that, 
should the owner decide to 
open the unit, the warranty 
is immediately void. 

The block diagram ap- 
pears on a double fold-out 
page. The diagram section 
also contains brief descrip- 
tions of the various parts of 
the system. There is 1 small 
error on the block diagram. 
It does not show the lower- 
half of the address bus going 
to the cassette I/O (in- 
put/output) port which 
must be addressed to 
operate. 

A memory map for any 
computer system reveals lots 
of information. The memory 
map in this book shows 
hexadecimal addresses 0000 
thru FFFF, and indicates 
where the read-only 



memory, programmable 
memory, keyboard, and 
video display fall within the 
addressable space of the Z80 
processor. 

The memory map shown 
is for a Level I machine; 
it is necessary to 
figure out what the address 
usage would be for a Level 
II machine. 

The real substance of the 
book is the 'Theory of 
Operation" section. Each 
separate section of the 
TRS-80 is explained in 
detail. This section of the 
book is the largest, and the 
video-display logic subsec- 
tion is the largest within 
theory of operation. 

The TRS-80 uses some 
unusual design techniques 
and a few uncommon parts. 
An example of this is the 
memory-mapped keyboard. 
The theory behind these 
design techniques and 
unusual parts is explained 
clearly, so that a person 
who has never seen these 
things can readily under- 
stand them. 

Throughout the theory of 
operation section, many 
explanations are of the type: 
"gate X goes low causing 
gate Y to go high". This 
causes the reader to refer 
constantly to the schematics 
at the back of the book, 
necessitating a lot of irri- 
tating page turning which 
could have been avoided if 
that portion of the 
schematic had been 
reproduced on the page with 
the description. 

Scattered throughout this 
section are many timing 
diagrams which, when used 
with the schematics, make 
the circuit descriptions easier 
to understand. 

The "Adjustments and 
Troubleshooting" section is 
also filled with infor- 
mation. Included are power 
supply checks and adjust- 
ments; section isolation 
using a flowchart; processor 
problem isolation using a 
flowchart; and 
troubleshooting for the 
keyboard, video-display 
logic, cassette interface, and 
power supply. These 
troubleshooting sections 
contain hints, and suggest 
possible bad parts causing 



156 September 1979 © BYTE Publications Inc 



Circle 190 on inquiry card.. 



We're about to make 
a new name for ourselves 



Not that the old one was so bad. As 
Ithaca Audio, we've made quite a name for 
ourselves. As the source for CPU, memory, 
video display and disk controller boards to 
upgrade other makers' mainframes and 
peripherals. The company that makes 
those neat little RAM expansion kits. And 
the folks behind the world's only Z-80 
Pascal compiler. 

But as much as we've enjoyed im- 
proving other people's equipment, we've 
been quietly moving towards larger en- 
deavors, with a lot of encouragement from 
our customers. Listening to people's prob- 
lems, as well as their needs. And, as a prime 
mover behind the IEEE S-100 Bus Standard, 
answering some really knotty questions. 

One of the results is our new identity. 
And our first new product : the Inter- 
systems DPS-1. An IEEE S-100 compatible 
mainframe with features that live up to its 
looks. Dependable operation to 4 MHz. 
Twenty-card capacity. A modular power 



supply. And something no one else has— 
built-in breakpoints to give you a faster, 
more powerful tool for testing software as 
well as hardware. Directly accessible from 
an easy-to-use front panel that's as reliable 
as it is functional. In short, an intelligently- 
designed computer for the intelligent user. 

There's a lot more to Intersystems. In 
hardware. And software. All available 
through the nationwide dealer network 
we're now assembling. 

You can watch this magazine for 
updates. Or contact us directly for straight, 
friendly answers and detailed information 
from key staff people. Just the way you 
always have. Because even though we're 
making a new name for ourselves, we'll 
never forget who made it possible. 



Ithaca Intersystems Inc. 

1650 Hanshaw Road/R O. Box 91 

Ithaca, NY 14850/607-257-0190 



rr" ' " 



© 1979 Ithaca Intersystems Incorporated 



various problems. The 
subsection on video ailments 
contains a handy table that 
shows the frequency of the 
signals to be found at 17 dif- 
ferent logic gates in the 
video divider chain. There is 
also a small program and 
instructions for adjusting the 
horizontal and vertical 
centering. The power supply 
subsection has a table that 
shows the voltages on all the 
pins of the 2 723C voltage 
regulators. 

Perhaps the most inter- 
esting section in the book is 
the one entitled "The Out- 
side World". Here the hard- 
ware enthusiast can learn 
how to hook up an 
automatic back scratcher or 
cigarette lighter to the 
TRS-80. Two techniques of 
external circuit interfacing 
are presented: memory- 
mapped addressing and I/O 
port addressing. The authors 
were kind enough to include 
schematics for a coffeepot 
control using both techni- 
ques. While these particular 
examples may not interest 
everyone, they do serve to 
illustrate how easy it is to 
make your computer do 
things other than run pro- 
grams. Also included is a 
BASIC program to turn on 
the coffeepot. 

The last part of this sec- 
tion has a chart showing the 
signals present on each pin 
of the expansion connector 
and an explanation of the 



function of each pin. Armed 
with the information in this 
section, the hardware 
designer should be able to 
interface just about anything 
to the TRS-80. 

The "Parts List" section is 
just that! It contains many 
individual lists headed by 
the part type, such as 
resistors, capacitors, inte- 
grated circuits, etc. A part 
number is also given for 
each part. However, there is 
no correlation between these 
part numbers and Radio 
Shack catalog part numbers. 
For example, the technical 
manual number for a 
74LS74 flip-flop is 3102015, 
while the Radio Shack 
catalog number is 276-1919. 
Fortunately, with integrated 
circuits, a part number is 
not really needed as long as 
the part is marked with its 
standard 7400 series 
number. As for most of the 
other parts, it is possible to 
substitute for the part just 
by reading the part descrip- 
tion. 

The "Schematics" section 
contains information on dif- 
ferences in the read-only 
memory parts of Level I 
machines, as well as 3 
figures showing schematic 
diagrams. One diagram 
displays the logic on the 
small printed circuit that 
contains the read-only 
memory devices in Level II 
equipped TRS-80s. This 
board is attached by 



adhesive tape to the main 
printed circuit board. A rib- 
bon cable extends from it to 
the socket intended for the 
Level I read-only memory. 

The other 2 figures show 
different sections of the logic 
contained on the main 
printed circuit board and the 
keyboard printed circuit 
board. These figures appear 
on long, fold-out pages. The 
first page contains the Z80 
processor, 3-state buffers, 
memory, address decoding, 
and keyboard. The second 
page shows the electronic 
logic for the system clock, 
video display, cassette I/O, 
and power supply. Spare 
gates are shown on both 
sheets. The schematics are 
well drawn, clear, and easy 
to read. They become rather 
awkward, however, when 
stretched out on a 
workbench that is probably 
already inhabited by the 
opened TRS-80 and the 
associated test equipment. I 
would have preferred the 
schematics split into at least 
4 pages. 

The book is written in a 
clear, easygoing style. 
[However, the authors often 
use engineering jargon where 
it would have been simpler 
to use plain English . . . 
RSS] The authors are not 
identified. Scattered here 
and there in the manual are 
many valuable trouble- 
shooting tips of a general 
nature. (An example is the 



paragraph on checking open 
collector outputs.) All of the 
figures in the book are large 
and easy to read. Except for 
the previously mentioned 
criticism of the main 
schematic, I consider this a 
plus. 

Conspicuous in its absence 
is a discussion of the video 
monitor. No schematic is 
given, nor is its operation 
discussed. I consider this to 
be the only major fault with 
the manual, one that surely 
will be corrected with the 
next revision. Also absent is 
a schematic of the power 
supply. 

As mentioned earlier, the 
intent of this book is not to 
give an education in digital 
logic. It does not even 
attempt to impart 
knowledge about the inner 
workings of the Z80 pro- 
cessor. That is beyond the 
scope of the manual. Nor 
does it explain what is con- 
tained in read-only 
memory. Software is men- 
tioned only in passing. What 
the book does teach is how 
all the various devices work 
together to form the 
TRS-80. Despite its faults, I 
consider this manual a 
valuable addition to the 
library of any hardware- 
oriented TRS-80 owner. ■ 



Ken Fordham 
7612 La Mesita Ct 
Tampa FL 33615 




A VIEW OF THE CLASSICS 




The first Micro Works PSB-08 PROM Board was assembled and burned in over two years ago— eons in the micro world. Designed 
as an efficient, cost-effective EPROM storage system for the SWTPC 6800, its flexibility accomodates all the new S-50 computers 
on the market— SWTPC 6809, GIMIX, MSI and Smoke Signal Broadcasting. The 2708 EPROM remains an inexpensive, capable 
media for storage of subroutines, I/O handlers, monitors and even BASIC interpreters while the cost and availability of 2716s still 
don't justify their purchase. PSB-08 has space for up to 8 2708 EPROMS and the following exclusive features: 

* 1K "scratch pad" RAM— more than enough temporary storage capacity for any program requiring up to 8K of PROM 

* Dip-switch addressable PROM and RAM, to start on any 8K boundary in memory 

* I/O select capability lets you move the I/O locations to any unused 1K block in EPROM memory space, permitting memory 
expansion to a full 56K contiguous user RAM 

Originally intended for use with 6800-based system software, the PSB-08 will continue to be a valuable tool for years to come with 
And the relocatable I/O feature lets you keep your 6800 system up-to-date. 



your 6809 
THE 



mO©D^§> 



The past two years have seen many microcomputer products come and go. In our history, there have 
been no takers on the PSB-08's warranty. Like the classics, our PROM board endures. Price: $1 19.95; 
regulated + 12v.: $124.95 



P.O. BOX 11 1D, DEL MAR, CA 32014 



71 4-756-26B7 



158 September 1979 © BYTE Publications Inc 



Circle 231 on inquiry card. 



nnssp 



13 INCH COLOR VIDEO MONITOR 




PROUDLY ANNOUNCES THE REVOLUTIONARY 
Tl 99/4 PERSONAL/EDUCATIONAL COMPUTER! 



Superior color, music, sound and 
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a unique, revolutionary Solid State 
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Instrument's special Solid State 
Command Module Software. 



OPTIONAL SOLID 
STATE SPEECH 
SYNTHESIZER 
s 1 49.95 






SOLID STATE SOFTWARE 
COMMAND MODULE 



99/4 COMPUTER 
MAIN CONSOLE UNIT 



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And the future is now. 

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edjteable about computers and are looking for the 
most programming power and versatility for your 
money. Maybe you've just read about it, and want u> 
loam more. BUher way. you need to look closely at 
Texas Instruments TI-9W4 Home Computer. 

TheTI-O&tf was designed to be the first true home 
computer - skilled computer users and beRinners 
alike will Ik- aide ti. put it to effective use right away. 

If you know computers, you'll quickly see the 

difference in the Tl-99/4. 
Texas Instruments has taken those features 
you've been wanting- plus sour- von may not have 
heard about yet-and included them in one incredible, 
affordable computer system. TheTI-Dil/4 Rives you 
an unmatched combination of features ami caps* 
bilities, including: 

• Powerful TI-HAHK' - Built-in l.'1-digit, lloaiing 
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BASIC, but with special features anil extensions 
for color, sound and graphics. 

■ t'pln 72K total mi'mnri capacity- tflK RAM (Ran- 
dom Access Memory). 2<>K ROM (Read Only Memory) 
plus up to :!<IK ROM in TI's Solid State Software 
Command Modules. 

• Jfih UOM -Operating system. BASIC, floating 
point, sound and color graphics software are con- 
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• Iti-color graphics capability— Easy-tn-accesK, high- 
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• Music and sound effects - Provides outstanding 
audio capability. Build Ihree-note chords ami adjust 
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V«u can build notes with short, straightforward 
commands. Five octaves from 110 Hz (Hertz) 

to beyond 40,000 Hz. 

• Built-in equation calculator— Unique convenience 
feature helps you find quick solutions to everyday 
math problems, as well as complex scientific calcu- 
lations. Directly accessible from the keyboard. 



If you're new tocomputers, IheTI-99/l 
is for you. 

Vnu can begin using the Tl Home Computer litt 
minutes after you unpack it. Without any prcvi 



neof TI's Solid Stale Softwan 
ud touch a few keys. Step-by- 
displaycd right on the screen 



You simply * 

Command M 
step instruel 
So vou or jiir 
LhuTI-ttU/4. 



Two pioneering technological developments 
in particular set theTI-WI/l apart from the rest. 

Solid Stale Speech v ' -This optional speech synthe- 
sizer enables the Tl-!i!'/4 to literally speak- to provide 
verbal prompts and special messages to the user. 
Actually reproduces the human voice electronically. 
Hundreds of words are available, and plug-in word 
modules will add hundreds more, Tl 's exclusive 
technology lets you call up the words you want 
by simply typing them in. Outstanding voice clarity 
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Solid Stair Soli Hare 11 ' Command Modules -Available 
in U wide range of application areas, these optional 
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memory to your TI-9i)/-l. They let you use the TI 
Home Computer immediately, with no programming. 
Serious programmers will appreciate the lime and 
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they'll let you Introduce your family to the computer 
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pioneered by TI for use with its powerful program- 
mable calculators. 

A world of genuine, practical applications 
exist for the TI Home Computer right now. 

In addition to the many personal finance, home 
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fortheTI-99/4, there are also a variety of home 
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is a powerful problem-solving tool- an ideal solution 
where larger, more expensive computers would be 
impractical. 



Texas 
r R° Instruments 

Hr TI-99 4 
Home Computer 

ACCESSORIES TO BE AVAILABLE: 



32 Character Printer 
RS232 Peripheral Adaptor 
DISK STORAGE/MEMORY 
MANY COMMAND MODULES 



CALL OR WRITE FOR FULL PRODUCT 
INFORMATION AND LITERATURE 

99/4 Computer s 1150— 

(includes Console, Video Monitor, and Demo Module) 

SPEECH MODULE $149.95 

(263 Words, available OCT/NOV) 

COMMAND MODULES ... $ 20 to $ 60 



99/4 DEALER INQUIRIES INVITED— CONTACT NEECO FOR INFORMATION 



NEECO IS PLEASED TO ANNOUNCE THAT WE HAVE BEEN SELECTED AS ONE OF THE Tl 99/4 COMPUTER 
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NEECO 



NEW ENGLAND ELECTRONICS CO., INC. 

679 HIGHLAND AVE., NEEDHAM, MASS. 02194 
MON. - FRI. 9:30 - 5:30, EST, 



(617)449-1760 

MASTERCHARGE OR VISA ACCEPTED 
TELEX NUMBER 951021, NEECO 



Circle 289 on inquiry card. 



BYTE September 1979 159 



Handy Pulser 



Bob Chrisp 

3428 Executive Av 

Falls Church VA 22042 



Figure 1: Schematic for the Handy Pulser. 
Switches SW4 and SW5 allow selection of 
positive or negative going pulses. Switch 
SW2 is a momentary contact switch 
which allows single pulsing. All resistors 
are .25 W and all resistances are measured 
in ohms. All capacitor values are given in 
microfarads. 

+ 5V 
A 



Rl 
50K 



UK 



R2 

t50K 
] 



IC1 
555 



.001 

.01 

.1 

-)l- 



1.0 

■3r- 

10.0 



^ 



SW6 



-l n 

n i > ° 



|- SW2 



+5V 



IC3 
7407 



14 



^7 



VCC GND 

Al Q 



A2 



Bl 



IC2 



74122 
B2 Q 

CLR 



*.. 



R3 
I0K 



IC3 
7407 



$»■ 



+ 5V 



IC3 
7407 



■>« 



IC3 
7407 



^ 



IC3 
7407 



l|>! 




.001 

— )h 

.01 

h!i- 



10.0 



f 




+ 5V V SW5 PULSE 



f 



^h 



VAK-1 MOTHERBOARD 

• Designed specifically for use with the AIM-65, SYM-1, and KIM-1 microcomputers 

• Standard KIM-4* Bus 

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• All IC's are socketed 

• Provides separate jacks for one audio-cassette, TTY, and Power 

• Completely assembled (except for card-cage) 

We manufacture a complete line of high quality expansion boards. Use reader service 
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We also carry the SYM-1 
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ijm\jB>- 



'Product of MOS Technology 



ENTERPRISES 

INCORPORATED 



2967 W. Fairmount Avenue • Phoenix, AZ 85017 • (602) 265-7564 



160 September 1979 © BYTE Publications Inc 



Circle 325 on inquiry card. 



Most of us at one time or another 
have had the need for a TTL 
(transistor-transistor logic) pulser 
source for troubleshooting or circuit 
design. Since most of us are not af- 
fluent enough to afford sophisticated 
test equipment we will usually kludge 
a TTL oscillator or pulser when the 
need arises. However, the next time 
we need our handy little circuit we 
end up searching our goody box only 
to find that we have used the parts in 
another piece of equipment. 

What I have tried to put together is 
an inexpensive oscillator that 
hopefully will stay in 1 piece and be 
ready when needed. In an effort to 
keep it simple and inexpensive I have 
left out some of the niceties that are 
found in your more expensive com- 
mercial test gear: variable pulse level, 
variable offset, rise and fall time con- 
trol, double pulses, etc. 

Design 

Three integrated circuits form the 
basis of the oscillator: a 555 timer 
connected as an oscillator, a retrig- 
gerable oneshot and a hex driver. 
Potentiometers Rl and R2 in conjunc- 
tion with the capacitor selected by 
switch SWl determine the operating 
frequency of the 555. I used poten- 
tiometers for both resistances so that I 
could have control of the duty cycle. 
The equation for the operating fre- 
quency is given by: 

f= 1.44 



(R1 + 2(R2))C 



The output of the 555 is connected to 
a 74122 retriggerable oneshot. The 
use of the oneshot allows independent 
control of frequency with the 555 and 
independent control of pulse width 
with the 74122. The combination of 
the 2 integrated circuits lets you trig- 
ger your oscilloscope from one edge 
and the other edge triggers the 74122. 
The 7407 was included for drive 
capability. SW3 allows for single 
pulse operation and SW4 and SW5 
provide positive and negative sync 
and pulse outputs respectively. 

Construction 

The 3 integrated circuits were 
mounted on Micro Vectorbord using 
wire wrap sockets. The pull up 
resistors were mounted on the same 



board with wire wrap pins. The re- 
maining components were mounted 
on the front panel. I decided not to in- 
clude a power supply in this design 
because the pulser is always being 
used with a breadboard which has its 
own supply or it is being used on my 
processor. By using the supply of 
whatever I am working on I don't 
have to run extra ground leads. 

Variations 

If you anticipate doing a lot of 
work where you must be synchro- 
nized to an external signal, then SW6 
could be replaced with a single-pole 
triple throw switch with the third 
position being the output of a 7413 
Schmitt trigger. The input of the 
Schmitt trigger would be your exter- 
nal signal. 

Utilization 

There are 2 things to be careful 
about in the use of the Handy Pulser. 
One, there are certain combinations 
of operating frequency and pulse 
width that will give you a constant 1 
or output; two, make sure the delay 
between your oscilloscope sync and 
pulse output keeps you on the screen. 
Otherwise, you can be delayed right 
off the screen. 

Specifications 

With the values shown in figure 1 
the unit's specifications are: 

• Pulse repetition frequency .05 Hz 
thru 400 kHz 

• Pulse delay 2 /is thru 3 seconds 

• Pulse width 2 (is thru 5 seconds 

Final Comments 

As I mentioned before, I decided 
not to include a power supply in this 
design but rather use the supply of 
whatever I am working on. One pro- 
blem that arises is that most manufac- 
turers do not provide convenient 
places to pick up the +5 V and 
ground. Rather than install separate 
connectors on each card, I installed a 
5 V regulator with convenient con- 
nectors on the mainframe of my com- 
puter. This has proven to be a great 
asset. If nothing else, it is a handy 
place to find ground since the frame is 
not ground. I used an LM-309 
regulator with pin jacks and ter- 
minals.! 



Circle 70 on inquiry card. 




AND 
STUFF 





Computer terminals, business systems, 
lab components . . . they all need desks 
and enclosures. That's what we're all 
about. Computer Furniture and Acces- 
sories offers a standard line of furniture 
suitable for a wide variety of applica- 
tions. Handsome, rugged, economical 
furniture in all shapes, sizes and colors. 
Basic models shipped from stock in 
days, not months. And we're nice people 
to deal with. What more could you 
ask for? 



CF*A 



Computer Furniture and 

Accessories, Inc. 

1441 West 132nd Street 

Gardena, CA 90249 

(213)327-7710 



September 1979 © BYTE Publications Inc 161 



TRS-80 SOLUTIONS ! 



BUSINESS 

Appointment log by M. Kelleher. Perfect for the 
professional. Accepts name and address, meeting 
start and endings, subject matter, derives elapsed 
time. For Level II, 16K $9.95 

Payroll by Stephen Hebbler. Comprehensive 24 pg. 
manual with step-by-step instructions included in the 
package. Prints W2 and 941 information. Disk - 
$59.95. 

Mail List I by Michael Kelleher is the economy model 
of disk-based mailing list programs. Uses a single 
drive and handles up to 1400 names per disk, plus 
provisions for sorting options. 16K, D $19.95. 



| BUS-80 | | 

I The Business Software People® 

J Just about everything you need ... within 1 j 

year, participants receive programming for I 

i Inventory, Accounts Receivable, Accounts j 

Payable and General Ledger systems, plus I 



Payable and General Ledger systems, plus 
| Sales and Payroll. Complete documentation 
' and software on diskette, $200.00 



i 



ST 80 - Smart Terminal 

Lance Micklus 
Turns your TRS-80 into a computer terminal. 
Features include CONTROL key, REPEAT 
key, ESC key, RUN key and a functioning 
BREAK key. Lets you list incoming data on 
line printer. Reprogram RS-232-C switches 
from keyboard, making baud rate changes 
simple. Level II, 16K $49.95 
ST80D 

Lance Micklus 
Contains extensions for disk drive systems to 
exchange files with a timesharing computer 
or another TRS-80. Can be customized fy 
redefining translation tables. Can transmit 
any type of TRS-80 ASCII file, also binary 
files. A practical, full-feature terminal 
program of professional quality. For 32K disk 
systems $79.95. 



Mail List II by BUS-80. Complete mail list system for 
dual disk. Enter, update, merge, sort, and print 
mailing labels. D, 32K $99.95 

Small Business Bookkeeping by Roger W. Robitaille, 
is based on the Dome Bookkeeping Journal, sold for 
years in stationery and discount outlets. Level II, 4K 
with ($22.00) or without ($15.00) Dome journal. 

Small Business Bookkeeping For Disk by Miller 
Microcomputer Services and Roger W. Robitaille, Sr. 
Extended version. 32K Disk. With journal $31.95; 
without journal $24.95. 

Inventory S by Roger W. Robitaille, Sr. 240 stock 
items can be contained using the full 6 data areas and 
2 pieces of alpha information. Level II, 16K $25.00 

Inventory II. 2 Disk based program allows for 
creation, maintenance and review of over 2,000 items 
per clean diskette. Operates under Disk BASIC, DOS 
2.1 with minimum memory allocation. D, $59.95 

Electric Pencil by Michael Shrayer. A word 
processing system. Insertions, additions, deletions 
and corrections made more easily than with an 
editor's pencil. Perfect text printouts. Level II, 16K, 
$100.00. 32K Disk, $150.00 

Accounts Receivable II by S. Hebbler. Does your 
billing, provides running balance, tracks overdue 
accounts, custom message printing option, much 
MORE. Requires 32K 2-disk system $79.95 

General Ledger I by M. Kelleher. Establishes, 
defines, deletes and sorts up to 400 accounts. Up to 
200 entries per session. For small-to-medium 
businesses not requiring double entry books. A com- 
prehensive, flexible accounting system. Requires 
32K disk. $79.95. 

Inventory System 2.3 by M. Kelleher. One of small 
business management's most difficult problems 
brought under control. Keep current on price 
increases, shrinkage, low stock, profit margins. 
Program can handle up to 1,000 items per data 
diskette. Improved version, lower price. With 
documentation $99.95, 32K 2-disk. 

Text-80 by Frank Rowlett. Fully-documented text 
processing system for disk. Create, edit, move, 
delete, insert, change, print words or lines. D, 32K 
$59.95 

8080-Z80 Conversion by M. Kelleher. Permits you to 
enter 8080 codings and returns the Z80 equivalent. L 
II, 16K $15.00 

Basic Statistics by Steve Reisser. Pearson product- 
movement correlation coefficient, chi-square, Fisher 
T-test, sample analysis of variance, Z-scores and 
standard scores, with a random number generator 
built in to simulate data. L II, 16K $20.00 



WANTED 
USED TRS-80 EQUIPMENT! 
We buy and sell used equipment 
Sample Prices: 



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4K Level I 
16K Level II 
6K Interface 
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175 225 

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NEW! ALL TRS-80 EQUIPMENT, 10% OFF! 
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Step up to the amazing Exidy Sorcerer. 
Features high-resolution graphics, 64 x 30 
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Sorcerer power can be yours for $995 [8K 
RAM], $1145 [16K], and $150 per 16K 
additional. A wide range of system and 
application soltware is also available. 



! 



NEWDOS 

Apparat 



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DISK ERROR SOLVED! Stop blaming your 

I drive, fix your DOS with NEWDOS: an | 
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i improve reliability, and key bounce, enable j 
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with a minimum of 1 disk drive. $49.95 

I NEWDOS + ( 

| Includes all the features of the original | 

j NEWDOS and adds 7 new utilities, including j 

I SUPERZAP, Disk Editor/Assembler, Dis- I 

j assembler, and Level I BASIC for Disk. j 

! $99.95 ! 



ACTION GAMES 

Slalom by Denslo Hamlin. Choose between Slalom, 
Giant Slalom and Downhill. Level II. 16K $7.95 
Air Raid by Small System Software. High speed 
machine language program with large and small 
aircraft flying at different altitudes. Ground-based 
missile launcher aimed and fired from keyboard. 
Planes explode when hit, cause damage to nearby 
aircraft. Score tallied for hits or misses. Level I or II, 
4K $14.95. 

All Star Baseball by David Bohike, Level II, 16K 
$7.95 



Batter Up by David Bohike. Level II, 16K $5.95 
X-Wing Fighter II by Chris Freund. Piloting an 
X-wing fighter, you're out to destroy the Death Star! 
A new, improved version of an exciting space 
favorite. Level II, 16K. $9.95 

Ten Pin by Frank Rowlette. A game of coordination, 
the scoring is true to the rules of the sport. Level II, 
16K $7.95 

Taipan by Art Canfil. Sail the China seas, dodging 
pirates and cutthroats, to make your fortune trading 
in arms and opium. Level II, 16K. $9.95. 
Balloon Race by Dean Powell. High above the 
Atlantic, your balloon must be cleverly maneuvered 
with the prevailing winds to reach Paris. Level II, 
16K, $9.95. 



| 



ADVENTURES 

Scott Adams 



Feel as if you're manipulating HAL from 2001 
when you play these machine language 
games. Hardly any rules, finding out is part 
of the fun. Two adventures on 32K disk, 
$24.95. Tape - choose from Land Adventure, 
Pirate's Cove, Mission Impossible, The 
Count, and Voodoo Castle - $14.95 each. 



DOG STAR ADVENTURE 
| Lance Micklus 

j You're trapped aboard an enemy battlestar 

[ ... can you find the gold, rescue the princess, 

I discover the plans and safely escape? Level 

j II, 16K $9.95. 



J 



Journey To The Center Ot The Earth by Greg 
Hassett. Excellent introduction to the excitement of 
ADVENTURE. Written in BASIC for ease of 
understanding, yet fast and fun!!. Level II, 16K tape 
$7.95. 

Amazin' Mazes by Robert Wallace. Ever -changing 
maze situation. Level II, 16K $7.95 

Kamikaze by Russell Starkey. Command your ship 
against attacking suicide planes. Machine language 
graphics make this fast and fun! L II, 16K $7.95 

Space Battles by Level IV. Assume the role of 
Galactic mercenary, roaming the universe in search 
of enemy aliens and the bounty you reap from 
destroying their ships! Danger, thrills, fast action — 
and financial headaches as wel I ! Features three levels 
of play, fast, machine language graphics, real-time 
input, Level II, 16KTapeor32K Disk. Tape -$14.95; 
Disk -$19.95. 

MISCELLANEOUS 

Diskettes Dysan 104/1 Box of five, $24.95 + $1.00 

shipping. Verbatim, box of ten, $34.95 + $1.00 

shipping/handling. 

Z80 Instruction Handbook by Scelbi Publ. $4.95 

+ $1.00 shipping/handling. 

The BASIC Handbook by Dr. David A. Lien $14.95 + 
$1.00 shipping/handling. 

Percom Disk Drives. Single or dual, for TRS-80's. 
Reliable, high quality, priced $100 lower than 
comparable units! Single drive -$399.00; Dual Drive - 
$799.00; Cable (required) - $29.95. 

Floppy Armour Protective envelopes for shipping 
floppy disks, of high-density, ultra-lightweight 
polymer. 5-pack, $4.95 + $1.00 shipping/handling 



f 



16K MEMORY KITS 
Ithaca Audio 
8 tested, guaranteed 16K RAM's, amazing 
low price - $99.95. 



162 BYTE September 1979 



Circle 313 on inquiry card. 



Electronics Assistant by John Adamson. Profession- 
ally written. Will draw sample schematics and help 
you design active and passive low-, band-, and 
high-pass filters, coils, attenuator networks, and 
three types of impedance-matching networks. 
Extensive graphics, one key selection routine. Level 
II, 16K -$9.95. 

SIMULATIONS 

3-D Tic Tac Toe by Scott Adams. Three skill levels - 
author warns you to practice before tackling 
computer's third skill level. I or II, 16K $7.95 

Star Trek III. 3 by Lance Micklus. One of the most 
advanced Star Trek games ever written. Level II, 16K 
$14.95. 

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BYTE September 1979 163 



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Languages Fcpum 



Come From... continued 



R Lawrence Clark, 30303 Avenida de Calma, 
Rancho Palo Verdes CA 90274 

While I applaud Mr Bass' attempts to improve the 
BASIC language ("Languages Forum," April 1979 BYTE, 
page 238), he has completely missed the point of the 
COMEFROM statement. The primary goal of the 
COMEFROM is to eliminate GOTOs, which Dijkstra 
and many other advocates of structured programming 
consider harmful. If the statement can also be used to 
trace back execution during debugging, that is an unex- 
pected bonus. 

I provided a detailed description of the semantics of the 
COMEFROM in "A Linguistic Contribution to GOTO- 
less Programming" (Datamation, December 1973). Brief- 
ly, the statement: 

destination COMEFROM source 

is equivalent to the conventional: 

source GOTO destination 

where both source and destination are line numbers. 

The original article describes additional variants, 
which in BASIC would appear as the following: 



IF condition COMEFROM source 



and: 



ON variable COMEFROM sourcel, 
source2, ... , sourceN 

Because of the COMEFROM's potential for improving 
programming accuracy and readability, I feel it is impor- 
tant to clarify its proper usage. ■ 



Languages Forum is a feature which is intended as an interactive 
dialog about the design and implementation of languages for per- 
sonal computing. Statements and opinions submitted to this forum 
can be on any subject relevant to its purpose of fostering discussion 
and communication among BYTE readers on the subject of 
languages. We ask that all correspondents supply their full names 
and addresses to be printed with their commentaries. We also ask 
that correspondents supply their telephone numbers, which will not 
be printed. 



164 September 1979 © BYTE Publications Inc 



More on Multiple 
Conditions 



Scott Lawrence, 201B Lehman N SUCP, 
Potsdam NY 13676 



David Faught's letter titled "On Expressing Multiple Con- 
ditions" in the December 1978 BYTE Languages Forum, 
page 176, does a good job of illustrating the need for a 
language construct to deal with actions based on multiple 
conditions. I, too, found the means available in BASIC, 
FORTRAN, and COBOL (I am not yet familiar with Pascal) 
somewhat lacking. 

This need is met, however, in PL/I by the SELECT group. 
The basic syntax of this construct is shown in listing 1. 

Listing i. 

SELECT (expression); 

WHEN (expression-1 , expression-2) action-1 ; 
WHEN (expression-3 action-2; 
OTHERWISE action-3; 
END; 

When the SELECT statement is executed, the expression in 
parentheses is evaluated and the value is saved. The expres- 
sions in the WHEN statements are then evaluated one at a 
time in the order in which they appear. As each one is evalu- 
ated, its value is compared to the saved value. If a value is 
found that matches the saved value, the action specified by 
that WHEN statement is executed and no further expressions 
are evaluated. If none of the values match, the action speci- 
fied by the OTHERWISE statement is executed. 

The actions after the WHEN and OTHERWISE statements 
may be a simple statement, a compound such as IF . . . 
THEN . . . , a group of statements within a DO or BEGIN 
block, a GO TO statement, a null statement, a subroutine 
call, or even another SELECT group. After the action has 
been performed, control passes to the first statement after 
the END (unless the action specifies otherwise, of course). 

If the expression in the SELECT statement is omitted, the 
expressions in the WHEN statements are treated as logical 
statements and evaluated as a bit string. If any bit in the 
string is 1 (signifying true), the action is performed. (A=B 
would be evaluated as a 1 bit if A and B contained the same 
value.) Listing 2 shows an example of such a SELECT group. 

Listing 2. 

SELECT; 

WHEN (A<B) CALL LESSTHN; 
WHEN (A=B) CALL EQUAL; 
OTHERWISE CALL GRTRTHN; 
END; 

It is also possible to omit the OTHERWISE statement. If 
no WHEN statement is selected and there is no OTHERWISE 
statement, an error interrupt is caused. This is useful for 
catching critical data that has somehow gone out of the ac- 
ceptable range. 

I think this construct meets the needs which Mr Faught 
expressed, and is easier to implement than the alternative 
he suggests." 



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September 1979 © BYTE Publications Inc 165 



Data Abstractions and 
Program Correctness 



Earl E McCoy, U-157, University of Connecticut 
Storrs CT 06268 

One of the most interesting and informative aspects of 
BYTE magazine is the dialogue about programming 
languages found in the Languages Forums and Letters 
column. Many times these discussions are initiated by an 
article which included an example program in a par- 
ticular language. The ongoing debate about the strengths 
and weaknesses of various programming languages is 
most informative and useful to those people who know 
only one language well. 

The recent article concerning queuing theory, "Queu- 
ing Theory Part Is Queue Representation" (April 1979 
BYTE, page 132), by Len Gorney provides a good vehicle 
for discussion. My comments are not to be taken as 
criticism of author Gorney, but as comentary concerning 
BASIC as compared to a contemporary language such as 
Pascal. It is important for programmers to understand 
that the difference between BASIC (and FORTRAN) and 
Pascal is not just one of degree, but one of type as well. 

One of the most important and fundamental concepts 
in modern software engineering practice is that of data- 
abstraction. The data-abstraction has great influence 



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upon program correctness. A data-abstraction is defined 
as a data-structure and the set of operations that may be 
legally performed upon it. An example in the queuing 
theory context is the data-abstraction queue, for which a 
data-structure must exist to store its contents, and for 
which 5 operations are allowed: initialization, insertion, 
deletion, overflow, and underflow. The semantic mean- 
ing of these operations is also defined, but will not be 
repeated here so as to avoid duplication of the Gorney 
article. 

How is a queue to be implemented in a programming 
language? It would be simple if a programming language 
included a data-structure of type queue but, to my 
knowledge, none do. In general there exists an infinite 
number of data-structures of potential interest, and no 
language could include them all. Instead, any particular 
language usually includes only a small set of data-struc- 
tures such as reals, integers, and characters; and arrays, 
records, and files of these structures. No insurmountable 
problem exists, however, because a data-structure of in- 
terest can usually be constructed from these existing 
primitive data-structures. Thus one may construct a 
queue data-structure by using an array and 2 integers 
(head and tail pointers). 

Notice that the implementation of a queue data-struc- 
ture in the manner just described does not result in the 
data-abstraction of a queue: the program manipulating 
the array and the pointers is in no way restricted to the 5 
legal queue operations. It is this lack of operation restric- 
tion that can result in program incorrectness, particularly 
in large programs undergoing maintenance. For example, 
because the data-structure is global(ie: exposed to the en- 
tire program) a "fix" for a particular problem may result 
in a new problem elsewhere within the program. 

Pascal addresses the data-abstraction concept directly 
by allowing the declaration of more than just variables 
(as opposed to other languages). This includes constant 
variables, which may never be the target of an assign- 
ment operation, and more importantly, the declaration 
of novel data types. For example in Pascal we might 
define waitingline to be a variable of type queue by the 
following: 

var waitingline : queue; 

Note that we might want more than 1 variable of type 
queue. This is allowed, as are the arrays of queues and so 
on. The contents stored within the queue may be items of 
type integer: 

var items : integer; 

However, they might be persons: 

var items : persons; 

Note that integer is a defined data-structure in Pascal, but 
that queue and persons are not. Before discussing this fur- 
ther, a comment on what advantage this brings the pro- 
grammer is appropriate. 

Recall the definition of a data-abstraction: a data- 
structure and the legal operations upon it. By writing 
procedures and functions for the legal operations upon a 
data-structure we are, in effect, implementing a data- 



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abstraction. For example, in the queuing context, we may 
define procedures for initialization, insertion and dele- 
tion, and functions for overflow and underflow. Program 
correctness is enhanced if these are programmed correctly 
because queues can then be manipulated only in legal 
ways. Remember that queues will be passed to these 
subroutines — not the underlying array data-structure. 

Back to the problem of implementing the user declared 
data-structure types in Pascal. This is accomplished by 
declaring data-structures at a level above variables: 

type persons = . . . 

queue = . . . 

Here the dots indicate the data-structures necessary to 
implement the type in Pascal. For example, in the queu- 
ing theory context, we might have: 

type queue = record 

head, tail : . . maxlength; 
full, empty : boolean; 

contents : array [0 . . maxlength] of integer; 
end; 

Here maxlength is a constant declared earlier in the pro- 
gram which indicates the legal subrange of the integer 
variables head and tail (used as pointers); full and empty 
are logical variables indicating the status of the queue; 
and contents is an array storing the contents of the queue. 
In this case the queue is storing integers, but it need not 
— it could just as well be persons: 

contents: array [0 . . maxlength} of persons; 

Of course, the meaning of persons would have to be 
declared earlier within the type statement for this to be 
legal Pascal. 

After the user declared data-structures are defined, 
variables of these types can be declared as follows: 

var waitingline : array [1 . . 3] of queue; 
teller 1: queue; 

These 4 queues are restricted to the definition of queue as 
shown above. If necessary, we might declare more than 1 
type of queue (ie: storing a different type of contents) if 
the problem context makes that appropriate. 

Listing 1 shows Pascal procedures and functions im- 
plementing the 5 legal queue operations. Note that the 
parameters are a and b. A change of the b type declara- 
tion is all that is necessary to make these programs 
workable for a different type of contents. An important 
point: there is no need to initialize the contents of the 
queue to a particular value and use this value to decide 
how to manipulate the pointers, as is implied by the 
Gorney article. In fact, by doing so a programmer is sow- 
ing the seeds for future disasters. If Mr Gorney 's queue is 
ever exposed to a value of -9, the program may fail. 
Clearly, making correct operation dependant upon the 
avoidance of certain potentially legal entries into the data 
structure is not good programming practice. 

At this time it is informative to step through the BASIC 
language equivalents in the Gorney article using some 
trial data. The complexity of program execution flow 



168 September 1979 © BYTE Publications Inc 




32K Board Pictured Above 



New RAM Prices. 

From The Dynamic Memory Company. 



16K— $249 
48K— $500 



32K— $375 
64K— $625 



Ever since we started making 
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ago we have continued to lower 
our prices to stay competitive. 
Due to your confidence in us, we 
are again able to lower our 
prices! Our reliability has been 
proven by months of superior 
performance in thousands of 
installations. Our low-power boards 
are being used by quality-minded 
systems manufacturers across the 
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4MHz boards now available. 

After receiving hundreds of 
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come up with a new version of our 
board which runs on 4MHz Z-80 
systems. It wasn't easy to come 
up with a high speed board which 
would operate as reliably as our 
450ns version, but after months of 
careful design and testing, we did 
it. The price of the 250ns board is 
$10 per 16K additional. 

Circle 45 on inquiry card. 



All of our features remain. 

Our boards didn't become great 
sellers only because of the price. 
We still offer you our deselect 
feature which allows our RAM to 
overlap with any fixed memory 
areas in your system. Also, the 
RAM area of our board is fully 
socketed so that you can expand 
the board yourself. 

Other standard features include: 
plug selectable addressing on 1 6K 
boundaries (shorting plugs are 
placed over wire-wrap pins to 
address the board — located on 
the top of the board for easy 
changes), S-100 and Z-80 
compatability and totally invisible 
refresh — no wait states. 

Fully assembled, tested, and 
guaranteed. 

All of our boards go through a 
rigorous testing procedure. They 
are then placed on burn-in running 
a series of memory tests to detect 
any other possible faults. After you 
receive the board, you are backed 
by us with a one year warrantee. 



Low power consumption keeps 
your computer from "losing its 
cool." 

The total power consumption of 
our 1 6K board is typically less 
than 4 watts ( + 8V @ 300ma, 
+ 1 6V @ 1 50ma and - 1 6V @ 
20ma). Boards with additional 
memory typically increase power 
consumption only 1 watt per 1 6K! 

Standard S-100 Interface. 

Our board is designed to 
interface with any standard S-100 
CPU. All of the timing of the board 
is independent of the processor ' 
chip, and the board is set up for 
different processors by changing 
two plugs on the board. 

Contact your local dealer. 

To find out more about our RAM 
boards, contact your local dealer. 
If he is unable to help you, call or 
write us for a fast response. 
Central Data Corporation, 1 207 
North Hagan Street, Champaign, IL 
61820. (217) 359-8010 

Central Data 

BYTE September 1979 169 



Circle 226 on inquiry card. 



E^^^^E- 


_ FORTRAN 






SPEED 




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makes mental execution exhausting and error-prone — 
which is exactly the point: BASIC programs are not as 
simple as they seem. 

The data-abstraction is complete when a Pascal pro- 
gram uses the 5 legal operations upon its variables of type 
queue. Examples are: 

initialize (tellerl); 



if not fullq (tellerl) 

then insert (teller, items); 



repeat 

delete (tellerl, items); 
write (items) 
until emptyq (tellerl); 



Note that the programmer has the responsibility to test 
for overflow or underflow before inserting or deleting 
items from the queue. This is true even though the respec- 
tive procedures do nothing for these operational 
mistakes. 



Listing 1: This simple Pascal program defines the data type 
queue and then describes the 5 legal operations on that data 
type. 

procedure initialize (var a : queue); 
begin 

a. head : = 0; 
a. tail : = 0; 
a. full := false; 
a.empty : = true; 
end; {of initialize} 
procedure insert (var a : queue; b : integer ); 
begin 
with a do 
if not full 
then begin 

empty : = false; 
contents [tail] : = b; 

tail:= (tail + 1) MOD (maxlength + 1); 
if tail = head 
then full : = true; 
end; 
end; {of insert] 
procedure delete (var a ; queue; var b : integer ); 
begin 
with a do 
if not empty 
then begin 
full : = false; 
b := contents [ head ]; 
head : = (head + 1) MOD maxlength + 1); 
if head = tail 
then empfy := true; 
end; 
end; {of delete} 
function fullq ( a : queue ) : boolean; 
begin 

if a.full 

then fullq : = true 
else fullq : = false; 
end; {of fullq} 
function emptyq (a : queue ) : boolean; 
begin 

if a.empty 

then emptyq := true 
else emptyq := false; 
end; {of emptyqs} 



170 September 1979 © BYTE Publications Inc Circle 394 on inquiry card. 



Circle 205 on inquiry card. 



Listing 2: The data stack can also be defined in a Pascal pro- 
gram. It is left as an exercise to the reader to translate this pro- 
gram into BASIC or FORTRAN and compare the understand- 
ability of the 2 programs. 

type stack = record 

top : 1 . . maxlength; 
full, empty : boolean; 

contents : array [1 . . maxlength] of integer; 
end; 
procedure initialize (Var a : stack ); 
begin 

a. full := false; 
a.empty : = true; 
a. top : = 1; 
end; {of initialize) 
procedure push (var a ; stack; b : integer); 
begin 
with a do 
if not full 
then begin 
empty : - false; 
contents [top] : = b; 
if top < > maxlength 
then top : = top + 1 
else full : = true; 
end; 
end; {of push] 
procedure pop (var a ; stack; var b : integer ) : boolean; 
begin 
with a do 
if not empty 
then begin 
full ; = false; 
b : = contentsftop]; 
if topo 1 
then fop ; = top - 1 
else empty ;= true; 
end; 
end; {of pop) 
function fullstk ( a : stack ) : boolean; 
begin 

if a.full 
then fullstk := true 
else fullstk ;= false; 
end; {of fullstk) 
function emptystk ( a : stack ) : boolean; 
begin 

if a.empty 
then emptystk : = true 
else emptystk := false; 
end; {of emptystk) 



In summary, the data-abstraction is an important con- 
cept that greatly enhances program correctness. The 
Pascal programming language includes this concept; 
BASIC does not. My point again: the simplicity of 
BASIC is a red herring — it encourages sloppy program- 
ming and error-prone programs. A contemporary lan- 
guage like Pascal is explicity designed to encourage error- 
free program development, therefore it is worth learning 
and using. One more point: experienced Pascal program- 
mers know that the language includes pointers as a data 
type so the queue data-abstraction could be implemented 
even more easily than shown here. This particular 
method was chosen to correspond to the approach taken 
by the Gorney article. 

Just as a queue is an FIFO (first in, first out) data- 
abstraction, a stack is an LIFO (last in, first out) data- 
abstraction. Listing 2 shows a Pascal type declaration 
and the subroutines that are necessary to implement the 
legal operations upon a stack. These are included in the 
hope that readers may implement this data-abstraction in 
BASIC or FORTRAN and then compare for themselves 
the relative merits of these 2 languages to Pascal. ■ 



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NO TAXES on out-of-state shipments. 
FREE Surface delivery available in the U.S. 
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Radio Shack® store. 



Circle 314 on inquiry card. September 1979 © BYTE Publications lnc 171 



MAXIMUM VALUE 
FOR YOUR DOLLAR 

NORTH STAR COMPUTER PRODUCTS 

HORIZON1 16K KIT $1275.00 

1 6K RAM BOARD KIT $ 250.00 

32K RAM BOARD KIT $ 475.00 

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CC Tel: (219) 255-3408 2E 



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Metnorex 
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Circle 294 on inquiry card. 




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Microsette also offers professional 
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! (800) 258-5485 

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Dealers welcomed. Well established program. 

to rA-l 

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Circle 218 on inquiry card. 



Circle 19 on inquiry card. 



GODBOUT .SLASHES STfiTiC 
MEMORY PRICES fjGfilD: 



Econoram * unkits are now at their lowest prices ever. 

What's an "unkit"? It's a standard Econoram board that has all 
sockets and bypass caps pre-soldered in place. To complete assembly, 
the user simply solders in a few other parts, and inserts all ICs into their 
sockets. The result: A one-evening project that saves money while 
offering true CompuPro/Econoram quality for those on a budget. 
Static technology used throughout; all boards except Econoram VI 
run with 4 MHz systems. Same 1 year limited warranty, same great 
specs as our regular boards. 

Speaking of regular boards, we offer assembled /tested models and boards 
qualified under our high-reliability Certified System Component (CSC) pro- 
gram (200 hour burn-in, immediate replacement in event of failure within 1 year 
of invoice date). Refer to chart below for pricing. 




SI 

iii^-9 l SiS i iN 



Name 


Storage 


Buss 


Configuration 


Unkit 


Assm 


CSC 


Econoram HA 


8KX8 


S-100 


2-4K blocks 


$149 


$179 


$239 


Econoram IV 


16KX8 


S-100 


1-16K 


$269 


$329 


$429 


Econoram VI 


12KX8 


H8 


1-8K, 1-4K 


$200 


$270 


n/a 


Econoram VIIA-16 


16KX8 


S-100 


2-4K, 1-8K 


$279 


$339 


$439 


Econoram VIIA-24 


24KX8 


S-100 


2-4K, 2-8K 


$398 


$485 


$605 


Econoram IX- 16 


16KX8 


Dig Grp 


2-4K, 1-8K 


$319 


$379 


n/a 


Econoram IX-32 


32KX8 


Dig Grp 


2-4K, 1-8K, 1-16K 


$559 


$639 


n/a 


Econoram X 


32KX8 


S-100 


2-8K, 1-16K 


$529 


$649 


$789 


Econoram XI 


32KX8 


SBC 


2-8K, 1-16K 


n/a 


n/a 


$1050 



BANK SELECT MEMORIES (for Alpha Micro Systems, Marinchip, etc.) 

Econoram XII-16 16K X 8 S-100 2 ind. banks** $329 $419 $519 

Econoram XII-24 24K X 8 S-100 2 ind. banks** $429 $539 $649 

Econoram XIII 32K X 8 S-100 2 ind. banks** $559 $699 $849 

'Econoram is a trademark of Bill Godbout Electronics 

* 'Econoram XII-16 and -24 have 2 independent banks addressable on 8K boundaries; Econoram XIII has 2 independent banks addressable on 16K boundaries. 

— Did someon e say extended addressing? 16 bit CPUs? All we'll say is that Econoram XIV is coming soon — 

1 16K MEMORY *' 
EXPANSION SET 

— was $109, now 

only $87.20! 

And that's for a Godbout quality pro- 
duct. DIP shunts included, 250 ns chips, 
and crystal-clear instructions make expan- 
sion a snap in Radio Shack-80, Apple, 
and Exidy Sorcerer computers. Low 
power chips used exclusively. 

••••••••••••••••• 



ECONORAM II V 18 SLOT *• 

CLOSEOUT-$ 129 unkit I MOTHERBOARDS 

(3/ $375), $155 assm I UNKIT CLOSEOUT 

- was $124, t 



This is a limited quantity item — first come, 
first served. Our brand new Econoram HA is 

out, but even by today's standards the original 
Econoram II is an excellent memory. 2 MHz 
operation, low power, configuration as two inde- 
pendent 4K blocks, and one of the best track 
records in the industry for reliable and cost- 
effective operation. Easy one-evening assembly, 
1 year limited warranty on all components. 

••••••••••••••••••••••A 



now only $109 

With all edge connectors pre-soldered in 
place for painless assembly. Includes on 
board active termination. Coming soon: 
new 12 slot motherboard and an 18 slot 
double terminated model that can han- 
I die 12 MHz CPUs! , 

••••••••••••••••• 



OTHER COMPUTER PRODUCTS: 

2708 EROM BOARD UNKIT $85 

4 independently addressable 4K blocks, with selective disable for each block. 
Built to CompuPro/Econoram standards (dipswitch addressing, top quality 
board, sockets wove -soldered in place), and includes dipswitch selectable jump 
start built right into the board. Includes al! support chips and manual, but does not 
include EROMs. 

ACTIVE TERMINATOR KIT $34.50 

As written up by Craig Anderton in the April '79 issue of Kilobaud Microcom- 
puting. Our much imitated design plugs into any S-100 motherboard to reduce 
ringing, crosstalk, noise, and other buss-related problems. 



TERMS: Cal res add tax. Allow 5% ship- 
ping, excess refunded. VISA* /Master- 
charge^ call our 24 hour order desk at 
(415) 562-0636. COD OK with street ad- 
dress for UPS. Prices good through cover 
month of magazine. 

Circle 150 on inquiry card. 



(ompuPro 

Box 2355, Oakland Airport, CA 94614 



"INTERFACER" S-100 I/O BOARD 

$189 unkit, $249 assembled and tested. Dual serial port with 2 full duplex 
parallel ports for RS-232 handshake; EIA232C line drivers and receivers (1488, 
1489) along with current loop (20 mA) and TTL signals on both ports. On board 
crystal controlled timebase with independently selectable Baud rate generators for 
each part (up to 19.2 KBaud). This board has hardware LSI UARTs that don't tie 
up the computer's CPU. operates with 2 to 5 MHz systems, includes software pro- 
grammable UART parameters/ interrupt enables/handshaking lines, offers provi- 
sion for custom frequency compensation on both receive and transmit sides to ac- 
commodate varying speed/noise situations or unusual cable lengths . . . and even 
all this isn't the full story on what this no-excuses board can do for you. We think 
this product is a real winner; check one out in person, you'll see what we mean. 



from 




(PGUP 

ELECTRONICS 



FREE FLYER: Weil be giad to tell you 
more than the space of this ad permits. 
Just send your name and address, we'll 
take care of the rest. If you're in a hurry, 
enclose 4K in stamps for 1st class 
delivery. 

BYTE September 1979 173 



SAVE MORE THAN 20% 




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Circle 16 on inquiry card. 



SOFTWARE FOR 



APPLE IE 



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Send check or money order to: 

TECHNICAL SOFTWARE INC 

P O Box 73043 

Melaine, Louisiana 70033 



THE COMPETITION 

is south of the border 
WHAT ARE THEY UP TO NOW? 

Microprocessor sales in LATIN 
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22/23 Old Burlington Street, 
London W1X 1R1. England. 



Circle 41 on Inquiry card. 



PRECISION MICROCOMPUTER 
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MODEL MP04 




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DOCUMENTATION PROBLEMS? 

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Circle 295 on inquiry card. 



tinyFORTH 



tlnyFORTH is the cassette oriented version of 
the dictionary based computer language 
called FORTH. 

tlnyFORTH includes these FORTH features: 
s Dictionary-oriented structured high-level 
language *• Built-in assembler and text 
editor ^ Interpreter for quick program de- 
velopment s Compiler for fast execution 
^ tinyFORTH and FORTH programs are inter- 
changeable s Cassette tape input and 
output s Enhanced graphics s Faster 
& more powerful than level II BASIC ^ More 
compact programs than BASIC ^ Easy to 
use. 

tlnyFORTH cassette for TRS-80 and full docu- 
mentation $29.95 

Documentation only $ 9.95 

All orders are fully guaranteed. Add S1.50 for 
postage and handling. Order with check, 
money order. Visa, or Mastercharge. Specify 
TRS-BO level when ordering. 

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Reston, VA 22090 



Circle 365 on inquiry card. 



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Circle 333 on inquiry card. 



6800 BASIC 
CROSS REFERENCE 

Greatly reduces the time to examine and 
modify a BASIC program with this com- 
plete CROSS REFERENCE listing of a 
BASIC program. 

Reads a BASIC program from disc and 
selectively provides source listing and 
complete SORTED CROSS REFERENCE 
of all VARIABLES - FUNCTIONS ■ GOTO 
and GOSGB statements. 

Program is written in assemble using 
SMOKE SIGNAL MINI DISK SYSTEM. 
Specify as either TSC or CO-RES assem- 
ble source format. 

Complete source and object is on a 5Va 
mini diskette for $ 1 4.95. 



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Unless you enjoy challenging micro 
software development projects with 
some of the fastest growing commer- 
cial systems manufacturers in the U.S. 
Our clients offer generous salaries, 
flexible hours, profit sharing, etc. to 
experienced or degreed assembly 
programmers in areas such as 
communications, diagnostics, text 
editing, graphics, compiler, and O.S. 
design. Starting salaries 18-28K. All 
fees, relocation and interviewing 
expenses assumed by the companies. 

Please contact Dave Adams 
(617) 246-2815 (collect calls 
accepted). N.E. Recruiters, 6 
Lakeside Office Park, Wakefield, 
MA 01880. 

Fee paid consultants 



Circle 329 on inquiry card. 



Circle 357 on inquiry card. 



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BUSINESS 

CRS - Cliant Record System. A complete program package for the Insurance agent. CRS will 
provide you with very fast online access to your client records, print reports and mail labels, and give 
you all the information you will need to increase your sales through the use of CRS as a MARKETING 
TOOL. 

CRS stores a complete record for each client that includes the name, address, telephone #, as well 
as provisions for customer #, salesman #and up to six policies (expandable if needed). The policy 
information is complete with both the type of converege and the company that is underwriting it, as 
well as exp. date, premium, tarm, and payment schedule. You also have a remark field. 

You can search the files by any field, and CRS supports a powerful 'sieve' search to provide you 
with all the information you need to increase insurance sales. CRS comes with two|2} users manuals, 
one for the owner, and one for office personnel! (minimal system: one drive, 40K RAM starting 
ZQOOH) $250.00 (manual: $40.00) 

TEXT PROCESSORS 

TFS - Text Formatting System. At last a full featured text processor for NorthSter that you can 
rely on! TFS has left & fight margin justification, page numbering, chaptering, page headings, 
centering, paged output & MORE. Supports powerful text manipulations including: global & local 
'search and change,' file merges and block moves. This means that you can restructure your text file 
at any time to look the way you want it to, you can even 'chain' files together from disc for 
documents larger than your current memory. 

TFS is completely load and so' therefore you can start using it at once. You get two(2) users 
manuals: one is a Quick Start manual to get you going in minutes, the other is an in depth study of 
TFS. (TFS requires RAM from 0O0OH to 2D0OH) $75.00 (manual only: $20.00) 



ASSEMBLERS 

ARIAN - A complete 8001) assembler that interfaces directly to your DOS. ARIAN is completely 
'load and go'. Features include: dynamic file and RAM allocation, custom disc and RAM commend cap 
ability, several library routines directly accessable by the user. Also, a complete text editor, and 
system executive. ARIAN is both powerful and easy to learn and use; it is an assembler that you can 
grow with. Comes complete with a 51 page users manual (ARIAN requires RAM from 0O00H to 
2000H) $50.00 (manual alone: $10.00) 

ARIAN Utility Package -Several disc based utilities. Includes a complete DEBUG Package: 
$50.00 

PROGRAMMING LANGUAGES 

'Tiny' PASCAL - This is the famous Chung/Yuen Tiny' PASCAL. FAST • ELEGANT - 
STRUCTURED. Local and global variables plus procedure and function independence make Tiny' 
PASCAL grBBt for high spooif applications. Compiles to 8080 code that executes up to 25 times faster 
than BASIC. You also rocieve SOURCE to Tiny' PASCAL written in PASCAL. This means that you can 
compile the compiler! Add features, relocate, etc. (you will need 36k to do this) $40.00 

n C n r UTILITIES 

U t B E - (Does Everything But Eat!) This is a must for NorthSter users. You can: COMPACT & 
EXPAND BASIC programs. Compacting removes unnecessary spaces and remarks. This saves 
memory and makes for programs run faster. Expanding puts them back again. 

Cross-reference BASIC programs by variables and transfer statements. 

Global substitutions of variable names in BASIC programs. 

Formatted print outs of BASIC programs as well. $40.00 




SPECIFY SINGLE OR DOUBLE DENSITY 

ALL ORDERS PREPAID OR C.O.D. 

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50 pages plus Each Month! 



Crunchers Corner — Bryant * A Look at 
the SWTPC CT-82 — Ferguson * 6800 
Relative Branch Calculation (Hand) — 
Berenbon « Relative Calculator (Machine) 

— Heatherington * Maillist (Disk) — Lilly * 
Modems — Schuman * Semiconductor - 
Part 2 — Kinzer * Locate — Pigford * A20 
MA, Printer-SWTPC — Perdue * AS-50 
Monitor Board — Pentecost * TSC Basic 
for 6800 — Shirk * Plus Much-Much More! 



Crunchers Corner — Bryant « A 
Case forthe Small DOS — Mauch 

* MF-68 Motor Fix — Sorrels * 
Transfer (FLEX 1 to 2 or 5) — 
Womack « 6800 Delay — Beren- 
bon * Make Like a 6809 — Fein- 
tuch * Games (Basic) — Harmon 

* Boot (Flex-BFD) — Puckett * 
Freeze Display (SSB) —Johnson 

* Paper Tape Reader — Adams * 
FLEX'" Fixes and Much More! 



P3ul 




MAGAZINE COMPARISON 

(2 years) 

Monthly Averages 

6800 Articles 



KB 

7.8 



TOTAL 
PAGES- 



BYTE CC DOBB'S 

6.4 2.7 2.2 19.1 ea. mo. 

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Circle 337 on inquiry card. 



BYTE September 1979 175 



Circle 236 on inquiry card. 



IMMEDIATE 
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WE'VE GOT YOU COVERED! 

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ware and your investment. Save mainte- 
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Covers come in hundreds of sizes each cus- 
tom designed to fit a particular model of termi- 
nal, CPU, Line Printer, Floppy Disk. They're a 
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save many times the cost in reduced mainte- 
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Cover Craft Dust Covers are available from 
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Event Cueoe 



In order fo gain optimum 
coverage of your organi- 
zation's computer con- 
ferences, seminars, work- 
shops, courses, etc, notice 
should reach our office at 
least three months in advance 
of the date of the event. En- 
tries should be sent to: Event 
Queue, BYTE Publications, 
70 Main St, Peterborough 
NH 03458. Each month we 
publish the current contents 
of the queue for the month of 
the cover date and the two 
following calendar months. 
Thus a given event may ap- 
pear as many as three times in 
this section if it is sent to us 
far enough in advance. 



SEPTEMBER 1979 



September 4-6 
International Conference 
and Exhibition on Engineer- 
ing Software, University of 
Southampton, England. The 
aim of this conference is to 
provide a forum for the 
presentation and discussion 
of recent advances in 
engineering software and to 
present a state-of-the-art in 
this field. The exhibition 
held in conjunction with the 
conference will cover all 
software products, services 
and equipment related to 
engineering software. Con- 
tact Dr R Adey, Engsoft, 6 
Cranbury PI, Southampton 
S02 0LG, ENGLAND. 

September 4-7 
Compcon Fall '79, Capital 
Hilton Hotel, Washington 
DC. This 18th Institute of 
Electronic and Electrical 
Engineers (IEEE) Computer 
Society International con- 
ference will present the latest 
developments in micropro- 
cessor architecture, support 
software, operating systems, 
and peripheral devices. Con- 
tact IEEE Computer Society, 



POB 639, Silver Spring MD 
20901. 

September 5-8 
Info/Asia, Ryutsu Center, 
Tokyo. This exposition will 
be devoted to information 
management, computers, 
word processing, and ad- 
vanced business equipment. 
The exposition will be ac- 
companied by a 4 day con- 
ference. Contact Clapp and 
Poliak Inc, 245 Park Ave, 
New York NY 10017. 

September 8 
2nd Annual Microcomputer 
Faire, Cullen College of 
Engineering, University of 
Houston. 70 exhibitors are 
expected at this computer 
fair. Contact Dr John L 
Hubisz, Division Natural 
Science and Math, College 
of the Mainland, Texas City 
TX 77590. 

September 12-13 
Gateway Computer and 
Office Systems Expo, Chase- 
Park Plaza Hotel, St Louis 
MO. This 2 day event will 
include a program of ex- 
hibits and conferences which 
will be open to data proces- 
ing and business profession- 
als. Contact The Conference 
Co, 60 Austin St, Newton 
MA 02160. 

September 18-20 
Wescon/79, St Francis 
Hotel, San Francisco CA. 
Contact Electronic Conven- 
tions Inc, 999 N Sepulveda 
Blvd, El Segundo CA 90245. 

September 24-26 
Minicomputers and 
Distributed Processing, New 
York NY. This 3 day 
seminar will examine the 
uses, economics, programm- 
ing and implementation of 
mini computers. Contact 
The University of Chicago, 
Center for Continuing 
Education, 1307 60th St, 
Chicago IL 60637. 



176 September 1979 © BYTE Publications Inc Circle 84 on inquiry card. 



September 25 
DP User Documentation 
Workshop, Kansas City 
MO. The workshop will 
focus on how to write DP 
user manuals. Emphasis is 
on analysis of specific user 
needs; planning and outlin- 
ing; and effective writing, 
illustration and packaging of 
documentation. Contact 
Progressive Communications 
Inc, The Alamo/310, 128 S 
Tejon St, Colorado Springs 
CO 80903. 

September 25-27 
Mini/Micro Conference and 
Exposition, Convention 
Center, Anaheim CA. Con- 
tact Robert D Rankin, 
Managing Director, Mini/- 
Micro Conference and Ex- 
position, 5528 E La Palma 
Ave, Suite 1A, Anaheim CA 
92807. 

September 25-27 
WPOE '79, San Jose Con- 
venter Center, San Jose CA. 
This show will be dedicated 
to word processing and 
office/business equipment, 
services and materials. Com- 
plementing the exhibit will 
be a 3 day executive con- 
ference program that focuses 
on emerging technologies 
and their applications in the 
office. Contact Cartlidge 
and Associates Inc, 491 
Macara Ave, Suite 1014, 
Sunnyvale CA 94086. 

September 25-28 
The 3rd Annual Data Entry 
Management Conference, 

Hyatt Regency, New 
Orleans LA. This conference 
will feature a full schedule 
of speakers, workshops, 
panels and vendor exhibits 
to assist the data entry pro- 
fessional. Contact Data En- 
try Management Associa- 
tion, POB 3231, Stamford 
CT 06905. 

September 26-29 
MIMI '79, Queen Elizabeth 
Hotel, Montreal, Canada. 
This symposium is intended 
as a forum for the presen- 
tation and discussion of re- 
cent advances in mini and 
microcomputers and their 
applications. Special em- 



phasis will be given to the 
theme of the conference 
"The Evolving Role of Minis 
and Micros Within 
Distributed Processing." 
Contact The Secretary, 
MIMI '79 Montreal, POB 
2481, Anaheim CA 92804. 

September 28-30 
Northeast Personal and 
Business Computer Show, 

Hynes Auditorium, Boston 
MA. Displays and exhibits 
will showcase microcom- 
puters and small computer 
systems of interest to 
businesspeople, hobbyists, 
professionals, etc. Lectures 
and seminars will be pre- 
sented for all categories and 
levels of enthusiasts, in- 
cluding introductory classes 
for novices. Contact North- 
east Exposition, POB 678, 
Brookline MA 02197. 



OCTOBER 1979 

October 1-3 
2nd Annual Symposium on 
Small Systems, Hilton Inn, 
Dallas TX. The symposium 
will consist of a blend of 
paper and panel discussions 
with major emphasis on 
microcomputer applications. 
Both hardware and software 
topics presenting state-of- 
the-art and state-of-the- 
industry aspects will be in- 
cluded. Contact Gerald 
Kane, Southern Methodist 
University, Dallas TX 75222. 

October 2-4 
NEPCON Central '79, 
O'Hare Exposition Center, 
Rosemont IL. This 10th 
annual exhibition and con- 
ference of electronic and 
microelectronic packaging 
and production equipment 
will feature displays of elec- 
tronic and microelectronic 
materials, hardware, tools, 
supplies and test instru- 
ments. Contact Industrial 
and Scientific Conference 
Management Inc, 222 W 
Adams St, Chicago IL 
60606. 

October 14-17 
International Data Proces- 
sing Conference and 



Circle 87 on inquiry card. 




CY-480 

UPC™: 

THE WORLD'S 

ONLY SINGLE CHIP 

LSI UNIVERSAL PRINTER 

CONTROLLER. NOW ONLY $25.00! 



The CY-480 UPC" . 
others don't! 



. providing the kind of service and special features 



And that means for off-the-shelf low prices, the CY-480 provides great flexibility and 
easy interfacing. Cybernetic Micro Systems' amazing CY-480 will control and 
interface standard 5" x 7" dot matrix printers (including those from Victor, LRC, 
Practical Automation and Amperex) with speeds up to 200 CPS! Operating from a 
single +5V power supply, the flexible CY-480 will interface easily with any 
microcomputer or minicomputer system through standard 8-bit ports. The CY-480 
accepts either serial (RS232C) or parallel ASCII input from the host system's data 
channel. 

The CY-480 replaces bulky, expensive, dedicated controllers. 

This small, single LSI package offers a 5 x 7 dot matrix character generator, full 
upper and lower case ASCII 96-character font, and a 48-character (expandable by 
daisy-chaining) internal line buffer storage. Standard features include a 10, 12 or 16 
characters/inch variable character density command, and horizontal and vertical 
independently expanded print command. The CY-480 provides graphic capability 
and includes a "flip-print" operating mode for 180° viewing, and ready lines provide 
full asynchronous communications with handshaking. 

Stock delivery . . . only $25 a single unit . . . send for YOURS today! 



CYBERNETIC MICRO SYSTEMS 

2378-B Walsh Ave., Santa Clara, CA 95050 
Phone (408) 249-9255. 



VISA and 

MASTER CHARGE accepted. 



From S-lOO to 
IEEE-488 







P&T-488+ S-100 computer = Intelligence 
for your Instrumentation System 

The P&T-488 permits an S-100 computer to operate as a talker, 
listener, or controller on the IEEE-488 instrumentation bus for 
less than half the cost of calculator-based systems. Software 
packages which give access to the 488 bus from high level lan- 
guages such as BASIC are available for CP/M, North Star DOS 
/BASIC, and Cromemco CDOS. Or "roll your own" system 
with the custom system package of assembly language drivers. 
P&T-488, assembled and tested, + any 
software package: $400 (domestic USA) 



Tro# 



PICKLES & TROUT 

P.O. BOX 1206, GOLETA, CA 93017. (805) 967-9563 



Circle 308 on inquiry card. September 1979 © BYTE Publications Inc 177 



Circle 288 on inquiry card. 





■ 
I 



OAE'S new PP-2708/16 
PROM Programmer is the 
only programmer with all 
these features: 

• Converts a PROM memory 
socket to a table top pro- 
grammer: No complex inter- 
facing to wire — just plug it 
into a 2708 memory socket* 

• A short subroutine sends 
data over the address lines 
to program the PROM 

• Programs 2 PROMS for less 
than the cost of a personal- 
ity module. (2708s and TMS 
2716s) 

• Connect 2 or more in paral- 
lel — super for production 
programming 

• Complete with DC to DC 
switching invertor and 10 



^*Pat s Pending 

turn cermet trimmers (for 
precision pulse width and 
amplitude alignment) 

• All packaged in a handsome 
aluminum case 

PP-2708/16 . .A & T$325. 

PP-2716 (Programs Intel's 
2716) A & T $295. 

OAE 

Oliver Advanced Engineering, Inc. 

676 West Wilson Avenue 

Glendale, Calif. 91203 

(213) 240-0080 



Main/Frames . $2 



•-»•..•.• 



Main/Frames „« m $200 



' 14 Basic Models Available 
' Assembled & Tested 
1 Power Supply: 
8v@15A, ± 16v@3A 

• 15 Slot Motherboard 
(connectors optional) 

• Card cage & guides 

» Fan, line cord, fuse, power 
& reset switches, EMI filter 

» 8v@30A, ± 16v@10A 
option on some mod 



Rack 
mounted 
from $200 



8" Floppy Main/Frame 
(includes power for drives 
and mainframe) from $365 



Write or call for our 
brochure which includes our 

application note: 
'Building Cheap Computers' 

INTEGRAND 

8474 Ave. 296 • Visalia, CA 93277 • (209) 733-9288 
We accept BankAmericard/Vlsa and MasterCharge 



Business Exposition, Town 
and Country Hotel, San 
Diego CA. Contact Data 
Processing Management 
Association, 505 Busse 
Highway, Park Ridge IL 
60068. 

October 15-18 
6th Information Manage- 
ment Exposition and Con- 
ference, New York Coli- 
seum, New York NY. Con- 
tact Clapp and Poliak Inc, 
245 Park Ave, New York 
NY 10017. 

October 15-19 
CPEUG 79, San Diego CA. 
This is the 15th meeting of 
the Computer Performance 
Evaluation Users Group 
sponsored by the National 
Bureau of Standards. Con- 
tact Judith G Abilock, The 
MITRE Corp, Metrek Div, 
1820 Dolley Madison Blvd, 
McLean VA 22102. 

October 16-18 
Understanding and Using 
Computer Graphics, Wash- 
ington DC. This course is for 
people who are now using, 
or making decisions about 
using computer graphics and 
its role in their organization. 
It will describe computer 
graphics, explain what hard- 
ware and software systems 
are available and give cost 
and performance com- 
parisons. Contact Frost and 
Sullivan, 106 Fulton St, New 
York NY 10038. 



October 20-21 
4th Annual Tidewater 
Hamfest-Computer Show- 
Flea Market, Cultural and 
Convention Center, Norfolk 
VA. Contact TRC, POB 
7101, Portsmouth VA 
23707. 

October 21-23 
New York State Association 
for Educational Data 
Systems Annual Conference, 

Granit Hotel, Kerhonksen 
NY. The theme of this con- 
ference is "Instructional 
Computing - Hardware/- 
Sof t ware /Courseware . " 
Contact Mary E Heagney, 
9201 Shore Rd, Brooklyn 
NY 11209. 



October 22-24 
The Association of Com- 
puter Programmers and 
Analysts 9th Annual Con- 
ference, Washington DC. 
The general theme of this 
conference is "Preparing 
Today for Tomorrow's New 
Technologies." Suppliers of 
software packages and com- 
puter services have been in- 
vited to describe and present 
their products in a series of 
structured presentations. 
Other sessions will cover 
trends in system technology 
and new methodologies for 
sharpening the professional 
skills of both systems 
analysts and programmers. 
Contact DBD Systems Inc, 
1500 N Beauregard St, Alex- 
andria VA 22311. 

October 22-24 
Computers in Aerospace 
Conference II, Hyatt House 
Hotel, Los Angeles CA. The 
conference theme, "Com- 
puter Technology for Space 
and Aeronautical Systems in 
the 80s," will be carried out 
by a series of panels, invited 
presentations, and con- 
tributed papers which will 
bring computer system 
technologists together with 
specialists in the application 
of embedded computers in 
space and aeronautics. Con- 
tact American Institute of 
Aeronautics and Astro- 
nautics, 1290 Ave of the 
Americas, New York NY 
10019. 

October 22-25 
ISA/79, O'Hare Exposition 
Center, Chicago IL. The 
conference theme, "Instru- 
mentation for Energy Alter- 
natives," will emphasize cur- 
rent practices in instrumen- 
tation design and implemen- 
tation. Contact Instrument 
Society of America, 400 
Stanwix St, Pittsburgh PA 
15222. 

October 22-26 
Pascal Programming for 
Mini and Microcomputers, 

Ramada Inn, Woburn MA. 
Sponsored by the 
Polytechnic Institute of New 
York and the Institute for 
Advanced Professional 
Studies, this workshop will 



178 September 1979 © BYTE Publications Inc Circle 177 on inquiry card. 



Circle 303 on inquiry card. 



include application ex- 
amples, lectures, informal 
sessions with the instructor, 
as well as individual and 
group programming ses- 
sions. Contact Professor 
Donald D French, Institute 
for Advanced Professional 
Studies, One Gateway Ctr, 
Newton MA 02158. 

October 28-30 
The 10th North American 
Computer Chess Champion- 
ship, Detroit Plaza, Detroit 
Michigan. Sponsored by the 
Association for Computing 
Machinery, this is a 4 round 
Swiss style tournament with 
the 1st 2 rounds to be 
played on October 28th (1 
PM and 7:30 PM), the 3rd 
on October 29th (7:30 PM) 
and the final round on Tues- 
day, October 30th (7:30 
PM). Contact Monroe 
Newborn, McGill Univer- 
sity, School of Computer 
Science, 805 Sherbrooke St 
W, Montreal PQ, 
CANADA H3A 2K6. 



NOVEMBER 1979 

October 29 - November 2 
Applied Interactive Com- 
puter Graphics, University 
of Maryland, College Park 
MD. This course is designed 
to cover the most important 
facets of graphics that are 
necessary to develop general 
graphic applications. 
Systems considerations are 
stressed, including con- 
figuration selection criteria 
and the pros and cons of 
off-the-shelf software. The 
most important factors and 
techniques are described for 
hardware, software and 
geometric modeling. Contact 
UCLA Extension, 10995 Le 
Conte Ave, Los Angeles CA 
90024. 

October 30 - November 1 
Interface West, Anaheim 
Convention Center, 
Anaheim CA. This 3rd 
annual West Coast small 
computer and office 
automation systems con- 
ference and exposition will 
feature over 100 company 
exhibits and 60 conference 



sessions covering a variety 
of data processing, word 
processing, data communica- 
tions, mangement hardware, 
software and service topics. 
Contact the Interface 
Group, 160 Speen St, Fram- 
ingham MA 01701. 

November 5-8 
Electronics Production 
Engineering Show, Kosami 
Exhibition Center, Seoul 
Korea. This international in- 
dustrial exposition will be 
devoted to the needs of 
manufacturers of electronic 
products in Korea. Contact 
Expoconsul, Clapp and 
Poliak International Sales 
Div, 420 Lexington Ave, 
New York NY 10017. 

November 6-8 
Midcon/79 Show and Con- 
vention. O'Hare Exposition 
Center and Hyatt Regency 
O'Hare, Chicago IL. Contact 
Electronic Conventions Inc, 
999 N Sepulveda Blvd, El 
Segundo CA 90245. 

November 6-8 
Institute of Electronic and 
Electrical Engineers (IEEE) 
3rd International Conference 
on Computer Software and 
Applications, The Palmer 
House, Chicago IL. Contact 
IEEE Computer Society, 
POB 639, Silver Spring MD 
20901. 

November 6-8 
3rs Digital Avionics Systems 
Conference, Fort Worth TX. 
This conference will probe 
the expectations and 
challenges of the digital 
revolution in avionics 
systems. Contact John C 
Ruth, Technical Program 
Chairman, POB 12628, Fort 
Worth TX 76116. 

November 12-14 
Computer Cryptography, 

The George Washington 
University, Washington DC. 
The objective of this course 
is to provide each partici- 
pant with a working 
knowledge of the use of 
cryptography in computer 
applications. Contact 
Continuing Education, 
George Washington Univer- 
sity, Washington DC 20052. ■ 



nrartinol 



HppUbUUUIIU 



BOOT- 
STRAP 



TURN ON YOUR TRS-80 DISK SYSTEM AND GO 
RIGHT INTO YOUR BASIC PROGRAM— YOUR 
TRS-80 WILL LOAD AND RUN PROGRAMS— BY 
ITSELF! Yes, with this unbelievable program your 
computer will take command of itself whenever 
power-on or reset is pressed. Go from DOS all the 
way into your Basic program, execute DOS or Basic 
commands, load and execute any machine-language 
programs or subroutines you need (such as printer 
drivers, machine language sorts, etc.), set your file 
buffers and memory size, then run any Basic pro- 
gram you want, without lifting another finger! 
BOOTSTRAP'S custom files make turn-key end-user 
applications simple! Requires disk system, works 
with DOS 2.1, 2.2 and NEVVDOS, completely docu- 
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PRACTICAL APPLICATIONS™ (415) 592 -6633 

1313 Laurel St., Suite 15, San Carlos, CA 94070 

□ Please send me TRS-80 BOOTSTRAP 
($15.95 each enclosed. Calif, residents add tax). 

□ Send your catalogs. 

Name 



Address. 
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is a trademark of Tandy Corp. 



State. 



-Zip. 



IOMMICOMPUTER PRODUCTS^ 

S-1 00 • TRS-80 |Ol 
APPLE • PET ^ 
ADD-ONS 



SPEECH SYNTHESIZER 



Quality, intelligible natural sounding COMPUTALKER 
Speech Synthesizer, a proven superior product since 1 976, 
comes complete with Load'N'Go software, user 
documentation and source programs. 

CT-1 S-1 00 Bus Plug-In $495 

CT-1T TRS-80 add on w/interconnecl to self contained 

enclosure 595 

CT-1 A Apple add on w/interconnect to self contained 

enclosure 595 

CT-1 P Pet add on w/interconnect to self contained 

enclosure 595 



FLEXIBLE DISK DRIVES 



Quality single or dual headed single or multi-drive 

configurations. Interconnects to self contained enclosures. 

Load'N'Go software and cable interconnects available 

when required. 

^,. „._, 35/40 TRACKS _ , _. . . 

Flip Sided Dual Sided 

40F1 Single Drive $400 40D1 Single Drive $500 

40F2 Two Drives $700 40D2 Two Drives $800 

40F3 Three Drives $990 40D3 Three Drives $1090 



ALL PRODUCTS 



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Please contact us for prompt, personal, professional service. 

DIAL (714) 

NO.1 OMNI 

(714)661-6664 

32422 Alipaz St., San Juan Capistrano, CA 92675 ^/ 

Circle 293 on inquiry card. September 1979 © BYTE Publications Inc 179 



THE ORIGINAL' 



• Personal 
C Computing 



Plan Now to attend 
the best Personal 
Computing show ever, 



Friday, Saturday, Sunday 
October 5 -6 -7th 
Philadelphia Civic Center 

Philadelphia, Pa. 




PC 79 



® 



Don't be confused — Other shows are copying us but 
they cannot equal us. We are the Original Personal 
Computing Show. Now in our Fourth Year. 



FEATURING: 

Major Exhibits 

from the 

Leading Companies 

• 

Personal Computing College 

with 80 Hours of 

Free Seminars by the 

Industry's Leading Speakers 

• 

Major Emphasis 

on 

Software Exhibits 

• 

2nd Annual 

Computer Music Festival 

Bigger! Better! 

• 

Antique 

Computing Devices 

on Display 

• 

See All the Latest 
Hardware 

• 

Business Systems 

and 
Business Software 



For more information and a 
Free subscription to our "PERSONAL 
COMPUTING" newspaper, send 
your name and address to: 



PERSONAL COMPUTING 79 

Rt. 1, Box 242 . Mays Landing, N.J. 08330 . 609/653-1188 

Industry TRADE SHOW on October 4th 
For exhibiting information please call or write. 



180 BYTE September 1979 



"THE ORIGINAL" 

> Personal 
C Computing 



EXHIBIT DATES & TIMES 



REGISTRATION 

at the door includes admission to all seminars. 

■ 3 days — October 5, 6, 7 $10.00 

■ Single day $5.00 

DEALER DAY 

Thursday, October 4 
also includes October 5, 6, 7 $15.00 

For Dealers, Purchasing Agents, Industry- 
Reps, Industry Officials only. 



2nd annual 

PERSONAL COMPUTER 

MUSIC FESTIVAL 

Saturday evening, October 6, 1979. 

Harrison Auditorium, Univ. of Pennsylvania, 
which is 1 block from the Philadelphia Civic 
Center. Doors open at 6:30 P.M. 

Featuring; Live demonstrations and perform- 
ances by leading computer musicians. 

A stereo record from last year's music festival 
will be on sale at the show. 

Daytime seminars and demonstrations at the 
Philadelphia Civic Center all day on Saturday, 
Oct. 6th, during the Personal Computing Show. 
800 Tickets will be on sale Friday and Saturday 
from P.A.C.S. at The Philadelphia Civic Center 
during the Personal Computing show and at 
Harrison Auditorium. 

The Personal Computer Music Festival is spon- 
sored by the Philadelphia Area Computer 
Society. For more information contact them 
at: P.O. Box 1954, Philadelphia, PA 19105. 



FRIDAY 

OCTOBER 5 

SATURDAY 

OCTOBER 6 

SUNDAY 

OCTOBER 7 



9 A.M. to 6 P.M. 

9A.M.to6P.M. 

10 A.M. to 5 P.M. 



HIT 


rEL 


Ar.rnMiwinnATinwR 












HILTON 


Single 


$46, 


Double $56 ■ 215-387-8333 
HOLIDAY INN 


Single 


$40, 


Double $46 ■ 215-387-8000 

Downtown 

PENN CENTER 


Single 


$36, 


Double $41 ■ 800-523-0909 
BEN FRANKLIN 


Single $32 


$39, 


Double $40-$47 ■ 215-922-8600 



PC '78 PHOTOS BY MARJ KIRK 




Speaker, David Ahl, Creative Computing magazine 




REMEMBER: Monday, Oct. 8th, is Columbus Day, <^ 
which gives an extra day to travel home. 




BYTE September 1979 181 



The AMSAT-GOLEM-80 



Joe Kasser 

11532 Stewart Ln 

Silver Spring MD 20904 



The AMSAT-GOLEM-80 Micro- 
computer Project provides a means 
for a group or club to put together an 
S-100 bus microcomputer in a 
relatively inexpensive manner. It is a 
modular system of hardware and 
software that can be built as a stand- 
alone system or superimposed on an 
existing S-100 machine. It is designed 
to be expandable and affordable. 
Many people who belong to micro- 
computer clubs, or who are learning 
about microprocessors, would like to 
own a microcomputer. However, they 
may not want to make the initial in- 
vestment of $500 to $1500 for the 
basic hardware. The AMSAT- 
GOLEM-80 is designed to be built in 
stages, as finances allow. Each stage 
of the AMSAT-GOLEM-80 is func- 
tionally complete and can verify the 
performance of the next stage. It is 
capable of incorporating any S-100 
card, contains a powerful debugging 
software package (AMS-80 version 
5.7), and the I/O (input/output) in- 
terface handlers for your system. It is 
designed to be flexible and easily 
customized to fit your requirements. 
This is recommended as a group pro- 
ject for 3 reasons: 1) to take advan- 
tage of bulk discounts in the purchase 
of hardware; 2) knowledgeable indiv- 
iduals are available to help others; 
and 3) test equipment can be shared. 

The order of construction is log- 
ical. Sections can be built and used to 
check out subsequent sections. Thus, 
a sequence of construction could be 
to build the cabinet and front-panel 
power supply, motherboard, console 
I/O card, programmable read-only 
memory card, programmable mem- 




Photo 1: The AMSAT-GOLEM-80 prototype computer. 



ory card (1), and processor card. At 
this level the basic AMS-80 program 
can be executed. The order of con- 
struction can be varied depending on 
the individual constructor's 
preference. The group can also build 
separate parts, put them together to 
get 1 machine working, then have the 
members build their own parts at 
their own pace. 

This technique of construction may 
not be the cheapest in the long run, 
but it is in the short run. It also allows 
nearly instant results, since the 
machine is doing something almost as 
soon as construction is begun. This is 
psychologically important, consider- 
ing the amount of money involved. It 
is difficult to decide which system is 
the cheapest in the long run. Building 
a microcomputer can be an open- 
ended drain on your finances because 
you will probably keep adding new 
memory and I/O peripherals. 



System Basics — Hardware 

The hardware is standard S-100 
bus circuit cards, but any Z80/8080 
processor card, memory card, or I/O 
card may be used. Circuitry is avail- 
able for a hardware front panel. This 
operates by putting the processor in 
the "hold" state and then taking over 
control of the bus lines. Memory and 
I/O ports can be exercised and 
checked out. A single-step feature is 
offered, as is jump start or boot start 
to a software monitor program. Sev- 
eral unique circuits are available for 
amateur radio use (eg: satellite 
tracking). 

Software 

The AMSAT-GOLEM-80 project is 
designed for active experimenters. It 
is expected that some machine- 
language programming will be per- 
formed on each machine. Thus, a full 
and expandable operating debug or 



182 September 1979 © BYTE Publications lnc 



monitor package is available. This 
program AMS-80 is a much improved 
and expanded version of AMS-80 
which was first published in the 
September 1976 issue of BYTE. Apart 
from the usual memory and register 
examine/change features, it incor- 
porates direct I/O operations, a 
disassembler mode, and keyboard- 
interruptable console operations. A 
list of the commands is shown in table 
1. All I/O drivers are contained 
within AMS-80, devices can be con- 
figured in software, and all I/O 
devices are accessed via a jump table. 
All utility routines used within the 
monitor are also available via jump 
tables, as shown in table 2. The hex- 
adecimal base address is F000 and the 
I/O driver section of the jump table is 
compatible with the Technical Design 
Laboratory's Z80 monitor. 

Also available is a floating-point 
math pack (Intel software library ver- 
sion relocated), a floating-point inter- 
preter; a macro-organized pseudo 
high-level language using a floating- 
point stack, and operating through 
the math pack and various other soft- 
ware, including radio teletypewriter 
(RTTY) reading programs which are 
mainly suited for amateur radio ap- 
plications. Patches for commercially 
available software (but not the actual 
software) are also available. These 
patches include Processor Tech- 
nology 5 K BASIC and North Star's 
disk operating system. 

The Power Supply 

The power supply is 1 of the 2 
single-point failure points in the 
system (the other is the processor). If 
it fails, the system is down. Thus, it 
should be overrated, cooled, and 
have a little spare capacity on hand. 
It should be capable of at least the 
following performance: 8 to 10 V at 
10 to 20 A, 16 to 18 V and —16 to 
—18 V at 2 A. The supply can be 
unregulated because each S-100 card 
carries voltage regulators as required. 
Use plenty of fuses; put 1 in the AC 
line and 1 in each of the DC supplies, 
as shown in figure 1. If you wish to 
add crowbar circuits, over-voltage 
protection, or shut-down circuits, 
that's fine. 

The Cabinet 

The cabinet is the part of the 



A 

B 

C 

D 

E 

F 

G 

H 

I I 

J 

K 

L 

M 

N 



P 

Q 

R 

S 

T 

U 

V 

w 

X 
Y 

z 



PRINT (MEMORY) IN ASCII 

* 

CONFIGURE I/O (INPUT/OUTPUT) DEVICE 
DISPLAY (MEMORY) IN HEXADECIMAL 
WRITE END OF FILE RECORD TO TAPE 
FILL (MEMORY) WITH CONSTANT 
GO TO LOCATION AND EXECUTE 
HEXADECIMAL MATH (SUM AND DIFFERENCES) 
NPUT FROM PORT TO CONSOLE 



PRINT (MEMORY) IN ASSEMBLY LANGUAGE 
MOVE BLOCK OF (MEMORY) 
PUNCH 6 INS LEADER TAPE 
OUTPUT TO PORT FROM CONSOLE 
SCAN TAPE 

* 

READ TAPE 

EXAMINE/CHANGE (MEMORY) 
PUT HEADER ON TAPE 
DISPLAY I/O CONFIGURATION 

VERIFY PROGRAMMABLE MEMORY BLOCK WORKS 
WRITE TO TAPE 
EXAMINE/CHANGE (REGISTERS) 



'Not assigned as yet. 



Table 1: AMS-80 version command list, version 5.7. Details of the operation of the 
commands are given in the description of AMS-80. 



Interactive Computer 
Graphics Software* 

For Microsoft and DEC* Fortran 



DEVIATIONS 




'<vSt< »> J''i "'{( *^> t i,n!', to sncra ■ 
mentft ! n high speec 

Self-re.;'""" •'! raster scan displays 
The complete p '•. written in 

standard Fortran IV, making it porta- 
ble to all computers, including mini 
and mi- ms. 

The entire set of over 20 subpro- 
grams. >r a CRT ter- 
minal and a Diablo 1620 printer, sells 
for $4 ! ier devic 
may I 

*Tr<irjem< *.rtf totp. 



above graphs arc examples, of the 

P. The top graph was made on a X-Y-Z 

refreshed display, the bottom graph 

made on a Diablo* 1620 printer." 



8705 N " i Road- 

Milwaukee, Wis. 53217 414/351-3404 

COMi 5 



Circle 53 on inquiry card. 



September 1979 © BYTE Publications Inc 183 



Circle 202 on inquiry card. 



THE WORLD'S FIRST 
ALL SOLID STATE 

VIRTUALLY 

INDESTRUCTIBLE 

FULLY ENCODED 

KEYBOARD. 

JUST $75. 




INTRODUCING THE TASA MODEL 55 
ASCII KEYBOARD. 

Imagine. A full capability, 128 position 
keyboard without a single moving part. 
Simply touch its surface and sophisticated 
electronics instantaneously transmit informa- 
tion to your computer. 

Imagine further. This state-of-the-art 
keyboard provides a TTL output that is fully 
encoded, verified, processed, and de- 
bounced on a 6-position, dual-sided card 
edge connector. Ready to plug in and 
operate. 

IF THE PRICE SOUNDS UNBELIEVABLE, 
REMEMBER WHAT SINGLE-CHIP TECHNOLOGY 
DID FOR THE CALCULATOR. 

The secret of the TASA keyboard's 
powerful performance and low price is fully 
integrated single-chip circuitry. Because 
there are no mechanical keys or flex switches 
to move up and down, all the electronics can 
be completely sealed inside the tough poly- 
carbonate case. This makes the TASA key- 
board virtually indestructible and immune to 
spills and rough handling. 

And since there are no moving parts, 
your TASA keyboard should have the same 
trouble-free life expectancy as a silicon chip. 
HERE ARE A FEW STATE-OF-THE-ART FEATURES: 

• Full 8-bit ASCII output and continuous 
strobe. 

• Low power: 18 V DC, 35 mA, built-in 
regulator. 

• Parallel output: active pull-down, direct 
TTL compatible (one load), open collector 
type. 

• Dimensions: 15"Lx6.25"Wx0.325" thin. 

• Easy hook-up to any system, including 
the Apple computer. 

ALSO AVAILABLE: 

The Model 16-A, a 16-key alphanumeric 
fully encoded, solid state 4x4 keyboard for 
use as a companion to the Model 55, or as a 
stand-alone data entry unit. 
TRY THE TASA KEYBOARD FOR 10 DAYS. 

Enclose payment with the order form. 
Connect the TASA keyboard to your com- 
puter and use it for 10 days. If you don't 
agree that this keyboard is worth many times 
the price, simply return it to us. Your money 
will be refunded in full. 



r 



PLEASE SEND THE FOLLOWING: 

□ TASA Model 55ASCII keyboard. . $75. 

□ TASA Model 55 with stand and con- 
nector $93. 

D TASA Model 16-A keyboard $55. 

Add $4. for shipping and handling. 

Enclosed is my check or M.O. for $ 

or Mastercharge/VISA # 

expires 

name 

ADDRESS _ 

CITY STATE ZIP 



KML 



■ MiHKfTi*r*: 

P.O. BOX 1237 LOS ALTOS, CA 94022 



AMS80: 



ORG 


OFOOOH 


<R> 


JMP 


CUSTOM 


START OF SOFTWARE 


JMP 


CONSI 


CONSOLE TO <A> 


JMP 


RDR 


READER TO <A> 


JMP 


CONSO 


<C> TO CONSOLE (ASCII) 


JMP 


PUNCH 


<C> TO PUNCH (ASCII) 


JMP 


LIST 


<C> TO LIST (ASCII) 


JMP 


CSTS 


TEST CONSOLE STATUS 


JMP 


IOCHK 


DETERMINE I/O (INPUT/OUTPUT) CONFIGURATION 


JMP 


IOSET 


SET I/O CONFIGURATION 


JMP 


MEMCK 


FIND TOP OF USER AREA (PROGRAMMABLE 
MEMORY) 


JMP 


RESTART 


BREAKPOINT ENTRY 
ENTRY POINTS 


JMP 


START 


REENTER BMS-80 


JMP 


BEGIN 


BYPASS CUSTOMIZING AREA 







CONSOLE ROUTINES (INDIVIDUAL) 


JMP 


CHIN ; 


CONSOLE INPUT AND ECHO 


JMP 


CONSA ; 


<A> TO CONSOLE 


JMP 


TCSTS ; 


GOTO MON IF CONSOLE INTRPT 


JMP 


TCRET ; 


OUTPUT CR/LF 


JMP 


AOUT 


<A> TO CONSOLE 


JMP 


THXB 


OUTPUT <A> (HEXADECIMAL-2 DIGITS) 


JMP 


THXW 


OUTPUT <H/L> (HEXADECIMAL-4 DIGITS) 


JMP 


MSG 


OUTPUT TEXT 


JMP 


PCHK 


TEST FOR NULL INPUT CHAR 


JMP 


CONSB 


<B> TO CONSOLE (ASCII) 
PUNCH ROUTINES 


JMP 


PHXB 


<A> TO PUNCH (HEXADECIMAL) 


JMP 


LEAD 


PUNCH 6 INS LEADER TAPE 


JMP 


PCRET 


OUTPUT CR/LF TO PUNCH 


JMP 


PHXW 


OUTPUT H/L TO PUNCH 


JMP 


POB 


<B> TO PUNCH (ASCII) 
LIST ROUTINES 


JMP 


LHXW 


OUTPUT H/L TO LIST 


JMP 


LHXB 


<A> TO LIST (HEXADECIMAL) 


JMP 


LCRET 


OUTPUT CR/LF TO LIST 


JMP 


LOB 


<B> TO LIST (ASCII) 
UTILITY ROUTINES 


JMP 


CONV 


CONVERT HEXADECIMAL TO ASCII 


JMP 


NIBBLE 


CONVERT ASCII TO HEXADECIMAL 


JMP 


DONE 


TEST FOR COMPLETION 


JMP 


TIMER 


DELAY 


JMP 


SDEHL 


HL-DE 


JMP 


LOCMB 


LOCATE CONTROL BYTE IN PROGRAMMABLE 
MEMORY BLOCK 


JMP 


IRST 


RESET INTERRUPTS 


JMP 


BACON 


BAUDOT TO ASCII CONVERSION 


JMP 


ASCBD 


ASCII TO BAUDOT CONVERSION 


JMP 


$ 


SPACE FOR PATCHES 


JMP 


$ 





Table 2: AMS-80 interface jump table. The individual routines are discussed in detail in 
the description of AMS-80. 



system that your friends will see and 
admire. It should look presentable. 
The number of switches and lights on 
the front panel has been the subject of 
numerous debates. Those which are 
necessary are a power on/off switch, 
a boot switch, and a reset switch. If 
you are doing a lot of I/O program- 
ming (common in amateur radio 
applications), an output port and an 
input port (sense switches) are useful. 
Status lights, control bus lights, and 
data and address bus lights/switches 
are optional. One full hardware tester 
panel should be built within each 
group if no known working system or 
other method for troubleshooting the 
hardware is available. The prototype 



shown in the photograph contains the 
full hardware tester panel circuit and 
is built separately from the power 
supply. This has the advantage of 
portability. 

The Front Panel Interface 

This card interfaces the front panel 
switches and displays to the S-100 
bus. It is used when first building the 
system to check out the operation of 
the individual cards. Once AMS-80 is 
running, its usefulness is diminished 
until a hardware failure occurs that 
leaves the system up, but inhibits the 
processor from working properly (eg: 
a bus buffer or data-bit failing). The 
controls on the front panel will then 



184 



September 1979 © BYTE Publications Inc 



Ihe 

Data 

Duo* 

FromDTC 



&* 



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N? 



0" MS* 

> 6 > 









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^mims*^^. > ijj^efiTOB&nagn ',^^ygs»ggt<a ^^ 



tf 



* 




What you see is what you get. 

Our Model 382 Data Terminal lets you 
manipulate your data-or-words-in- 
process on an eye-level CRT before 
you commit printer time to it. The 382 
is a truly elegant terminal that integrates 
video display with a letter quality 
printer to save you time, paper and 
consumable supplies. 

On the screen you'll see 24 lines of 80 
characters, with separate field attribute 
characters. And in memory, ready to 
scroll up or down into view, are four full 
pages (96-lines). You can even store 
eight full pages if you don't need the 
field attribute symbols. 

Distributor information 
available. 



Circle 97 on inquiry card. 



The Data Daisy, too. 

The DTC 382 is also the first system you 
can buy that has the full ASCII 96- 
character metal print wheel, our 

Data Daisy. Crisp clarity, long-lived 
metal, and a full 96-character set! Just 
what dp and communications people 
have been asking for. Purchase or full 
maintenance lease pricing is available. 
Please contact your local dealer or DTC 
for complete pricing details. 



\\UHti. 




Get one and start enjoying: 

True proportional spacing 

Speeds up to 55 char/sec. 

Fast-throughput, automatic 

reverse typing 

Automatic underlining 

Shadow printing 

1200 baud (burst mode) for printer 

9600 baud for video display 

RS-232C 

Worldwide fast service 

Write, TWX or call for additional 
information: Data Terminals & 
Communications, 590 Division 
Street, Campbell, CA 95008. 
(408) 378-1112. TWX: (910) 590-2436. 
Toll free number: (1) 800-538-9779 



BYTE September 1979 185 



m*©** 



o 

GND 

(Z> 



v. 



10-12 
VAC 



RECTIFIER 



Fl 20A 

-of"Vx, L> 



; 100,000^ f 



) +BV 



-o 



RECTIFIER 



F2 2A 

— <r\ja — 



; 3000/iF 



'^77 



3000/iF 



F3 2A 
-cPoo — 



D, 



Figure 1: Typical S-100 computer power supply. 



allow the problem to be located in a 
swift manner. When in the run mode, 
the address lights also indicate the 
location of the software that is being 
currently executed. This is useful in 
determining exactly where your pro- 
gram is hung up during debugging. 



The Memory 

Any S-100 bus programmable 
read-only memory and program- 
mable memory card can be used. 
However, if you are using a card that 
places a limit on the time period that 
it can be addressed continuously (ie: 



NOW, FROM MOUNTAIN HARDWARE. 

THE 100,000 DAY CLOCK. 



■ ■.■■,■ <vv 



Put your S-100 Computer 
on the clock. 

A real time clock could double the 
utility of your computer. Time events 
in 100/nS increments for up to 100,000 
days (over 273 years). Program events 
for the same period with real time 
interrupts that permit pre- 
programmed activities to take 
place... without derailing on-going 
programs. Maintain a log of computer 
usage. Call up lists or appointments. 
Time and date printouts. Time events. An 
on-board battery keeps the clock running in 
the event of power outage. 

Mountain Hardware also offers a complete line 
of peripheral products for many fine computers 




23 




Available at your dealer's. Now. 

Mountain Hardware, Inc. 

300 Harvey West Blvd. 
Santa Cruz, CA 95060 (408) 429-8600 



one using dynamic programmable 
memories), you will have to modify 
the select signals from the front-panel 
interface card to convert these signals 
in a pulsed mode (gate the clock into 
the control signals). Shop around for 
a good group buy. AMS-80 requires 
at least 4 K bytes of programmable 
read-only memory. You may want to 
put additional software in program- 
mable read-only memory. 

The 8080 can access 64 K bytes of 
memory. Since most personal sys- 
tems do not contain a full 64 K bytes 
of memory, and 8080 software is non- 
relocatable by virtue of its absolute 
mode-addressing capability, several 
manufacturers have put out software 
modules at fixed allocations. The 
Radio Amateur Satellite Corporation 
(AMSAT) has developed a memory 
map for software, thus making all 
user written software compatible. 
Using the expandable idea, basic soft- 
ware can be executed in minimal 
memory systems. The memory 
assignment map is shown in table 3. 

The main user memory area is up- 
ward expandable from location 0. No 
matter how much memory is avail- 
able, software will run if written for 
low locations. Hexadecimal 0100 is a 
good starting location so that the in- 
terrupt service area is not overwritten 
by your customized software. 

As home systems are assembled, 
they tend to fall into 1 of 2 distinct 
configurations. There is the floppy 
disk system, having much program- 
mable memory and a minimal 
amount of programmable read-only 
memory in which programs are 
stored on disks and down-loaded into 
user memory for execution. The 
second type is the eraseable read-only 
memory (EROM) based system. 
EROMs and EROM cards are 
relatively inexpensive. Programs can 
be stored in EROM and executed via 
AMS-80. This type of system con- 
tains less user memory than the 
floppy disk system. Since EROM 
cards come in 16 K-byte blocks, it is 
desirable that such a block be incor- 
porated in the AMSAT-GOLEM-80 
system. This allows for inter- 
changeability and redundancy. For 
added flexibility, the chosen card 
should have user memory coexistence 
capability. Thus, a group system can 
be put together out of both types of 
configuration, with minimal con- 
flicts. This block is located between 
hexadecimal 8000 and BFFF. 



186 September 1979 © BYTE Publications Inc 



Circle 258 on inquiry card. 



The *1 5,995 System 




Are you tired of inadequate floppy systems and overpriced mini- 
computers? BASIC TIME offers an affordable Minicomputer System 
with 10MB hard disk storage, printer w /stand and CRT. All complete 
with desk enclosure. 



Since the introduction of our System B-100 in June of 
this year, we have had an overwhelming response 
from you, the minicomputer system buyer. The 
reason for this response is, when it comes down to 
price, you can't find a much better value nowadays in 
a Small Business Computer System than what we are 
offering. 

Our Central Processor is a 16-bit, single board unit 
with 65K bytes of memory, using a 2901 microcom- 
puter to emulate the Data General Nova instruction set. 

we offer 10MB of hard disk storage on two disks, 
one fixed and the other removable, to allow for 
backing up the system. 

The operating system comes complete with Business 
Basic integrated with a sophisticated file manage- 
ment system. It is easily programmable by first time 
users and it supports editor and all facilities/utilities 
to develop business application packages. We also 
include a variety of subroutines to make develop- 
ment easier. 

The system comes with a full function video display 
terminal that has a standard typewriter keyboard and 
a 10 key numeric pad. The display screen will display 
1920 characters (24 lines of 80 characters). 

We have an optional printer that prints letter 
quality type if your needs are in that area, included 

Circle 14 on inquiry card. 



with that option, at no additional cost, is a word 
processing package. 

We include a Ceneral Business software package 
that consists of: general ledger, accounts payable, 
accounts receivable, payroll and inventory control. 
We provide complete software documentation to 
allow the user to modify it to fit his own needs. There 
is no charge for the software. 

The B-100 is upgradeable for users that require 
multi-user and muli-tasking capabilities. However, we 
plan to introduce our System B-200 in November. 
This system will be capable of multi-user and multi- 
tasking and it will handle up to four CRT's and printers 
in any combination. 

we have complete Dealer and OEM packages which 
include: pricing information and Dealer/OEM agreements. 



basic 



tirn 



1215 E. El Segundo Boulevard 
El Segundo, California 90245 
213/322-4435 

BYTE September 1979 187 



FFFF 



FCOO 



FOOO 



E800 
DFFF 



DOOO 

CCOO 
BFFF 

8000 

0100 
0010 
0000 



AMS-80 Custom Area, 

I/O (input/output) handlers, including VDB-4 software 



AMS-80 Standard Area 



Floppy Disk I/O and Bootstrap Loader 



4 K-Byte, Programmable-Memory Area for Buffers, etc. 



Video-Display Memory Area 



16 K-Byte, Programmable Read-Only-Memory Area (preferably 
maskable) 



User Programmable-Memory-Program Area 



Interrupt Service Area, Interfaces, etc. 



AMS-80 Programmable-Memory Links 



Table 3: Memory assignment map for the AMS-80. 



The block can be used to contain 
programs that execute in those loca- 
tions, or copies of programs that ex- 
ecute when moved to programmable 
memory locations in low memory. 
This is ideal for programs that need to 
be executed in user memory, or for 
storing programs as a backup to the 
floppy disk unit in case it is not 
available at a particular time or loca- 
tion, such as a demonstration at a 
computerfest. 

Processor Technology's SOL soft- 
ware is written to reside at hex- 
adecimal C000. It can be placed in 
that area if desired. The video display 
programmable memory is located at 
CCOO. This makes it compatible with 
Processor Technology and SSM. 

A programmable memory area is 



assigned at hexadecimal DOOO. This 
allows the stack to be located outside 
of the main user area. The buffer 
areas for cassette I/O can be located 
in this area, as can any program- 
mable memory-dependent software 
that is required for your system. 
AMS-80 is designed to automatically 
locate the stack in an area of user 
memory above the video block. It 
also skips this area when a user pro- 
gram asks for the top of user 
memory. If no such block exists and 
the video area is used, AMS-80 will 
have to be customized to avoid the 
video programmable memory area 
during initialization. 

The Processor 

Any S-100 bus processor card can 



be used. Different cards have dif- 
ferent features. Some have jump start 
or bootstrap capability, some have 
interrupt ports, and some have both. 
Some are available already built, and 
others as kits or blank boards. 
Choose one that suits the needs of 
your group. 

Input/Output 

You will need (and AMS-80 is con- 
figured for) 4 classes of I/O (in- 
put/output) devices, a console, a 
high-speed data-input device 
(reader), a high-speed data-output 
device (punch), and a high-speed, 
ASCII output device (list). The 
AMS-80 software allows 4 physical 
devices to be assigned to each 
category of I/O device. The 
assignments are in software and may 
be changed under program control. 
Software is provided for a video- 
display board (Cybercom) as well as 
a Teletype interface. Audio tape is 
chosen for off-line program and data 
storage. A floppy disk drive can be 
added at will. 

All I/O operations are performed 
on a single character basis, either in 
or out. Kansas City Standard tones 
have been chosen as the audio re- 
cording standard. There is, however, 
1 basic difference between the use of 
paper and audio tape. Paper tape can 
be stopped between punches or reads, 
but audio tape cannot be efficiently 
stopped. Thus, the audio cassette 
routines contain "blocking" software 
that stores the individual characters 
in a user memory area (preferably 
between hexadecimal DOOO and E800, 
as shown in table 3). This blocking 
software is transparent to AMS-80. 
Software is provided for all I/O to 
the console or terminal, the punch, 
reader, or list devices. The routines 
are located within AMS-80 and are 
called indirectly via a jump table as 
shown in table 2. Routines are pro- 
vided to ouput ASCII data from 
either the B or C register, allowing 
existing commercial software to be 
patched to operate via AMS-80 with 
minimal changes. Routines are also 
provided to output the contents of the 
accumulator (8 bits) or the H/L 
register pair (16 bits) in hexadecimal 
code. Character input routines are 
also provided. Most of the routines 
are used within AMS-80. 

There are 2 reserved I/O ports 
within the system. These are front 



188 September 1979 © BYTE Publications Inc 




It 



it's on the dou 



INTRODUCING — LOUMAR MANAGEMENT SYSTEMS SOFTWARE 



a 



programs to give you a comprehensive package for business management 



The Loumar General Accounting System is a versatile, fully integrated software package designed for small and medium sized 
businesses. It is also suitable for CPA's and bookkeeping service films. 

The complete software system is composed of four main modules: GENERAL LEDGER, ACCOUNTS RECEIVABLE, ACCOUNTS 
PAYABLE AND PAYROLL. Each module may be used separately or in combination with any other module. Supplied on disk as 
runtime modules. Source not available. 

All software is written in CBASIC II and utilizes the powerful CP/M operating system. 
General system features include: 

Automatic posting to general journal • Strict error detection • Report production on demand • Consistent operating procedures • 
User oriented. No previous computer knowledge required • Designed by accounting professionals • Comprehensive, well pre- 
sented reports and manuals • Single or multiple client capabilities. 

HARDWARE SPECIFICATIONS PAYROLL: Up to 500 employees - $550. 

The end user's microcomputer must satisfy the following require ACCOUNTS RECEIVABLE: Up to 1000 customers and 1000 monthly 



transactions — $550 
ACCOUNTS PAYABLE: Up to 1000 vendors and 1300 monthly 

transactions - $400 
GENERAL LEDGER: Up to 200 accounts with 2000 entries - 

$450 



merits: 
48k RAM 

Dual floppy disk system 

Printer with tractor. All printing is done in 80 col. format 
CRT with at least a 64 character by 1 6 line display 
CP/M and CBASIC II 

Write lor our brochure — Dealerships still available 
Contact: Distributor 

MISSION CONTROL • 2008 WILSHIRE BOULEVARD, SANTA MONICA, CA 90403 • (213) 829-5137 

Circle 237 on inquiry card. BYTE September 1979 189 



Pin# 


Signal 


1 


Chassis Ground 


2 


Data From Terminal To Computer 


3 


Data From Computer To Terminal 


4 


Control Line #1 


5 


Status Line #1 


7 


Signal Return (Ground) 


8 


Control Line #2 


10 


+ 18 V Supply 


13 


-18 V Supply 


17 


20 mA Current Loop ( + ), Terminal To Computer 


20 


Status Line #2 


23 


20 mA Current Loop ( + ), Computer To Terminal 


24 


20 mA Current Loop (-), Terminal To Computer 


25 


20 mA Current Loop ( - ), Computer To Terminal 


Note: This is a modified RS-232 Interface. Signal Levels are as follows: 


Mark (Logic 


1) = -3 V to -12 V, Space (Logic 0) = +5 V to +12 V. 



Table 4: Connections to the serial port interface connector. 



1 


Chassis Ground 


2 


Data Port 1 Status Bit 


3 


Data Port 1 Control Bit 


4 


Data Port 1 Bit (LSB) 


5 


Data Port 1 Bit 1 


6 


Signal Return 


7 


Ground 


8 


N/C 


9 


+ 8 V Raw Power 


10 


Data Port 2 Bit 6 


11 


Data Port 2 Bit 7 


12 


Data Port 2 Status Bit 


12 


Data Port 2 Control Bit 


14 


Data Port 1 Bit 2 


15 


Data Port 1 Bit 3 


16 


Data Port 1 Bit 4 


17 


Data Port 1 Bit 5 


18 


Data Port 1 Bit 6 


19 


Data Port 1 Bit 7 


20 


Data Port 2 Bit 


21 


Data Port 2 Bit 1 


22 


Data Port 2 Bit 2 


23 


Data Port 2 Bit 3 


24 


Data Port 2 Bit 4 


25 


Data Port 2 Bit 5 


NOTE: All voltage levels are transistor-transistor logic compatible. The Data Lines are com- 


patible to the MITS convention. Port 1 is configured as an input port and port 2 as an 


ou 


tput port if bidirectional I/O port integrated circuits (such as 8255s) are not used. 



Table 5: Connections to the parallel port interface connector. 



panel (FF) and interrupt control port 
(FE). The front-panel address is used 
for both displays and switches. FF 
was chosen because of the simple 
hardware needed to decode it (1 
NAND gate), while FE was built into 
the processor card utilized in the pro- 
totype. 

Some standardization of the hard- 
ware is desirable in a group project. 
This allows 1 person to check out 
another person's hardware. It also 
allows different members of the 
group to interconnect their equip- 
ment for large demonstrations. 

Interfaces come in 2 types: serial 
and parallel. The following stan- 
dards, which are slightly modified 
versions of existing ones, are sug- 
gested for the AMSAT-GOLEM-80 
Project. 



Audio Signals 

All audio signals from the com- 
puter or interface boxes to and from 
cassette recorders are via phono 
plugs/sockets. The actual connectors 
on the tape recorder may be anything 
from miniature phone to DIN-type 
connectors. 

RF/Video Signals 

BNC-type connectors should be 
used to carry video to and from 
monitors. The BNC connector is 
small, quick to connect and discon- 
nect, and readily available world- 
wide. 

Digital Signals 

Digital signals come in 2 types: 
serial and parallel. Both types of 
interfaces should use 25-pin EIA-type 



connectors. The chassis connector on 
the computer will be female; the 
chassis connector on the remote 
device is male. Power can be fed 
down the cable from the computer to 
the remote device via the I/O cable. 
Having a female connection on the 
hot lead reduces the probability of 
short circuits. They can also be joined 
together to make larger ones, without 
the need for special adaptors. The 
serial connector assignments are 
based on the RS-232 interface. The 
pin assignments are shown in table 4. 
The parallel connector carries 1 input 
and 1 output port (8 bits each), plus 1 
pair of handshake signals. The signal 
pins are compatible to the MITS 
recommended ones. Power and 
ground are fed down the cables, thus 
the recommendation for fuses in the 3 
DC voltage lines. The parallel port in- 
terfaces are transistor-transistor logic 
(TTL) level, the serial port RS-232 
voltage levels (mark = negative, 
space = positive). The pin assign- 
ments are shown in table 5. 

AMS-80 

AMS-80 is a full, software-de- 
bugging program. It also contains the 
system I/O drivers and utility 
routines accessible via a jump table. 
The jump table approach is utilized so 
that user programs written using the 
utility routines within AMS-80 will 
not require reassembling, should a 
subsequent version of AMS-80 be 
released. The version that was 
previously published (September 
1976 BYTE) has undergone extensive 
modifications and has been relocated 
to the block of memory between hex- 
adecimal F000 and FF00. This allows 
many existing programs written for 
low, user memory area (such as MITS 
BASIC) to be run through the I/O 
drivers within AMS-80. It is thus 
possible to run a program in BASIC 
and have the ouput appear on the line 
printer (list device) or the console at 
will. The standard capacity existing 
in AMS-80 is shown in table 1. 

System Expansion 

The modular design of the 
AMSAT-GOLEM-80 system allows 
for operability at all stages of con- 
struction, once the initial stage is 
reached. Since a great deal of money 
is being spent, it would be encourag- 
ing to see it perform as soon as possi- 
ble. The initial stage, apart from the 
processor power supply and bus, 



190 September 1979 © BYTE Publications Inc 



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BYTE September 1979 191 



Circle 54 on inquiry card. 



Control 
System 

Software 



lection of software for anafyzin 
trol systems. The set includ« 
quency domain methods such as 
Bode and Root Locus algorithms, and 
modern start* variable methods. 

These programs will calculate the 
data for a given system, and then pro- 
duce a tabulated printed output, a 
graphical display on a printer, or both 
The programs include both the analy- 
sis subprograms and the printer plot- 
ter subprogram. 

• Bode Algorithm CS-B $100. 

• Root Locus Algorithm CS-R $100. 

• Time Response ..... .CS T $100. 

All of the above packages will run on a 
8080 or Z80f — based CP/M* system. 
^Trademark of ZHog trademark of CHgttal 



Research 





COMPCO is a software and hardware 
systems development house located 
In the Midwest. COMPCO has a 
variety of software products, and 
performs custom and contract 
programming. 

COMPCO is a distributor of ALTi 
Computer systems and also sells 
General Robotics LSI-11* systems 
^Trademark of Digital Equipment Corp. 

wompco 

8705 North Port Washington Road 
Milwaukee, Wis. 53217 414/351-3404 

COMPUTER SPECIALISTS 





Punch 


P = 3 
P = 2 








P=1 


Audio Cassette 






P = Console 




Reader 


R = 3 
R = 2 








R=1 


Audio Cassette 






R = 


Console 




List 


L = 3 








L = 2 


Baudot device (model 15) 






L=1 


Teletype Port 






L = 


Console 




Console 


C = 3 








C = 2 


Baudot Device (model 15) 






C=1 


Video Display Board/Keyboard 






c = o 


Teletype Port 




Video Di; 


>play Board 








V = 


Page With Line Foldover 






V=1 


Page Without Line Foldover 






V = 2 


Scroll With Line Foldover 






V = 3 


Scroll Without Line Foldover 





Table 6: AMS-80 I/O (input/output) allocations. 



comprises 4 K bytes of programmable 
read-only memory of user memory, 
and a terminal device. With this 
amount of hardware, you can run 
AMS-80, enter programs in memory 
in hexadecimal code via AMS-80, and 
learn a little about software. The ad- 
dition of some off-line memory, such 
as audio or paper-tape devices, 
allows you to run programs which re- 
quire up to 4 K bytes of memory. 
Such programs include Tiny BASIC, 
orbital calculations for amateur 
satellite locations, and various 
amateur radio programs. If you have 
a radio teletypewriter terminal unit 
(RTTY-TU), you can even tune your 
shortwave radio in to commercial or 
amateur Teletype stations, and 
display their transmissions on your 
terminal. 

If you get a modem interface and a 
second terminal, or use a video 
display/keyboard combination and a 
serial port/modem, you can make the 



basic system into a remote terminal 
for a large machine timesharing ser- 
vice, and access the computer at work 
from your home. Add another 4 or 8 
K bytes of user memory, and you can 
run text editors, assemblers, or an 8 K 
BASIC interpreter. This opens a new 
dimension in computing. You can 
play Star Trek, and run education 
and business software and advanced 
amateur radio programs, such as con- 
tests. Put 16 K bytes of user memory 
in your system and you can get a 
floppy disk unit for an added dimen- 
sion in computing. 

Off-Line Data Storage 

Off-line storage is storage for pro- 
grams and data that is external to the 
64 K bytes of accessible memory. It 
usually consists of audio tape, floppy 
disks, or paper tape. Floppy disk 
storage usually comes with an 
operating system and will not be 
discussed here. AMS-80 contains 



192 September 1979 <S BYTE Publications Inc 



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BYTE September 1979 193 



routines to store and read software 
from paper tape. Data is stored in In- 
tel hexadecimal format. Paper tape, 
although common in professional 
circles, is not cheap, and the readers 
and punches are expensive. However, 
inexpensive hand operated readers do 
exist, so paper tape is a convenient 
and easily mailable form of program 
storage (for chort programs). 

Paper tapes can be stopped under 
software control. Thus, when BASIC 
is reading and interpreting a pro- 
gram, it can stop the tape momen- 
tarily to process the line of source 
code. Audio cassettes cannot be stop- 
ped in such a manner. Other pro- 
grams, such as Assemblers or Editors, 
also have requirements for occasional 
inputs and outputs. Thus, AMS-80 
contains buffer cassette-driver soft- 
ware to enable the main program to 
think that it is reading or writing 
characters on an incremental basis. 
Data is stored on tape in blocks of 256 
characters. There is no format as 
such; the format is set by the main 
program because in this system the 
audio cassette is treated as if it is 
paper tape. This means that by using 



the Intel hexadecimal format and 
cassette buffer-driver routines in 
AMS-80, any paper-tape, cassette, or 
floppy disk system can read or write 
tapes and convert to and from the 
format needed for a particular 
operating system. A title command is 
put into AMS-80 to allow headings to 
be written on hexadecimal code 
blocks of tape so that they can be 
identified. 

Since even a 15-minute cassette 
tape can hold a lot of software, a 
command is provided within AMS-80 
to allow a tape to be scanned and a 
program found. The command trans- 
fers data from the reader to the punch 
device. It may be used to copy tapes 
or, if the console is assigned as the 
punch, it may be used to scan tapes 
and locate particular blocks. 

The number of data bytes in a 
block is 256. Each block is preceded 
and followed by a mark tone. This 
allows the tape to be stopped and 
started. The data is read to or written 
from the tape at 300 bps. 

If the system has error detection, 
error-detection bytes are put on the 
tape. For example, the Intel hex- 




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adecimal format checks each line of 
code for a read error. Each line as 
printed on the console is a block in 
itself. The data, address, and error 
detection bytes are output to the 
paper-tape punch. These bytes will be 
collected by the cassette buffer soft- 
ware which, when full, will write 256 
bytes on the audio tape. When 
reading that block back, it will read 
the entire block into a buffer. The In- 
tel hexadecimal format reader then 
gets the data on a character-by- 
character basis from the buffer, and 
checks for errors. 

The cassette storage medium is 
designed to be a paper-tape equiva- 
lent for information exchange. It is 
not designed to be part of an 
operating system, although an 
AMSAT flexible operating system 
may be available in the near future. 

Operating Systems 

Cassette and disk operating 
systems are currently available. 
These can be patched to operate 
through the AMS-80 I/O (input/out- 
put) drivers and hence improve them 
by allowing assignable I/O devices. 
AMS-80 is a paper-tape operating 
system in which the file storage and 
sorting is done by the operator. 

The advantages of software con- 
figured I/O can be seen in the follow- 
ing circumstances: BASIC is designed 
to operate via the console. Punch and 
reader operations are available for 
program storage, but the execution is 
usually via the console. With 
assignable I/O, the console ouput 
routine can be assigned to a line 
printer, and outputs obtained at high 
speed. Alternatively, different 
readers (paper and audio) can be 
assigned with no change in the BASIC 
interpreter software. 

The spare commands in AMS-80 
can be allocated to interface to the 
operating system. For example, "Q" 
could be assigned to execute a jump 
to the operating system. A command 
can be assigned to return to AMS-80, 
once in the operating system. These 
aspects of interfacing AMS-80 to 
operating systems will be discussed in 
detail later. 

Real-Time Operations 

Real-time operations are required 
for many tasks. The 8080 has the 
capability of directly distinguishing 
between 8 real-time interrupts. In the 
AMSAT-GOLEM-80, Interrupt is 



194 September 1979 © BYTE Publications Inc 



Circle 94 on inquiry card. 



equivalent to Reset, and Interrrupt 1 
is reserved for the breakpoint feature. 
The remaining interrupts are 
available for custom software. The 
time-of-day clock is not implemented 
in software, but rather in hardware, 
using an MOS digital-clock circuit. A 
number of floppy disk interfaces, 
North Star in particular, do not allow 
for interrupts during the disk read 
and write operations. Thus, a soft- 
ware clock would not be updated 
when running such a disk system. 
This means that no real-time opera- 
tions could be executed without 
reinitialization of the clock each time. 
Using a hardware clock, the time of 
day can be read at any time by using 
simple input statements from the I/O 
port assigned to the clock. 

Documentation 

Documentation is very important. 
Keep all of the instructions for the 
various kits in one place. Three-ring 
binders are inexpensive and can con- 
tain a large amount of information. If 
you need more than 1 binder, split the 
information logically, such as hard- 
ware, software, peripherals, etc. 
When you build and test cards, note 
any unusual or special things that you 
did. Note any voltage or other 
measurements you made. Keep a 
copy of test routines you used to 
initially test something. You may 
need them a few years later. The level 
of documentation should be better 
than that supplied with commercial 
equipment. It may help you sell the 
system. It is also important to docu- 
ment the operational aspects of the 
system. Document how it is con- 
figured (an example is shown in table 
6), and record the operating instruc- 
tions so that others can operate the 
system in your absence. Note which 
connector plugs into which socket. 
When in doubt, document it. 

Planning your Project 

Your requirements are going to dif- 
fer from those of other people. Your 
method of assembly can be the same, 
but can differ in details. There are 
many manufacturers of memory and 
I/O cards. Some are sold fully 
assembled and tested, some assem- 
bled, some as kits, and some as bare 
boards. Choosing the card that suits 
your needs at a particular time can 
reduce your cost. Remember that the 
software is hardware transparent; for 
example, a program designed to run 



in user memory at hexadecimal 
memory locations 0100 to 2000 will 
run in any type of working memory, 
no matter who manufactured it. 
Therefore, it does not matter if you 
use a Brand X product when the rest 
of the club uses a Brand Y. Just ensure 
that the specifications for addressing 
the card are the same. (Wait states do 
not matter. If you need an extra wait 
state, your software will take longer 
to execute, but you will probably 
never notice the difference.) 

The price of hardware is constantly 
falling. New cards are being intro- 
duced every month. It is possible to 
purchase a 32 K or 64 K-byte 
programmable-memory card 
populated by only 8 K bytes of 
memory circuits, and add the remain- 
ing integrated circuits as you need 
them. The price of the next 8 K bytes 
will probably be less than today's 
price. Purchase your hardware when 
you need it. Look around, compare 
the cards made by different manufac- 
turers, decide how their features will 
fit into your system, ask for advice at 
your club, and then make your pur- 
chase. For example, some processor 



cards come with vectored interrupt 
capability, and some with bootstrap 
start. 

Summary 

The details of the construction of 
the individual cards are not presented 
here because vendors supply their 
own information. In the AMSAT- 
GOLEM-80, the hardware is inter- 
changeable (within limits), and the 
actual manufacturer of any particular 
card is immaterial. The prototype has 
served to check our hardware and 
software for members of The Radio 
Amateur Satellite Corporation (AM- 
SAT) and the Chesapeake Microcom- 
puter Club Inc, who have set up a 
bulk purchase scheme for obtaining 
price reductions on hardware. 

This article has described an 
approach to building an S-100 com- 
puter that is incremental and afford- 
able, even though it may not be the 
lowest cost in the long run. The 
AMSAT-GOLEM-80 is an approach 
to a system. It may be built up as a 
stand-alone system, or it may be 
overlaid onto your existing hard- 
ware. ■ 



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September 1979 © BYTE Publications Inc 195 



Add Some Control 
to Your Computer 

An Output Port Tutorial 



Ken Barbier 

POB 1042 

Socorro NM 87801 



A virtually limitless number of 
devices can be controlled through a 
single output port using time multi- 
plexing techniques. A series of 8-bit 
bytes is fetched from a control buffer 
in memory, and output through a 
single port. On the receiving end, bus 
buffers present the data to all the 
devices in parallel, but unique strobes 
are supplied to each device in turn, so 
that it can latch its own data word. 

This technique is particularly 
useful if the devices are to be located 
some distance from the computer. 



DS»0 



The hardware shown in figure 1 has 
been used to control devices over 50 
feet from the computer without exotic 
line drivers and receivers. Since 
remote addresses for each device are 
generated by the hardware, only 8 
data lines and 1 strobe line are re- 
quired. For maximum noise immu- 
nity, shielded twisted pair cable 
should be used. 

Receive Hardware 

In figure 1, 16 external devices 
receive 1 8-bit byte apiece. Using the 



Intel 8080, this block of data will be 
transmitted in about 300 „S. The 
I/0(input/output) write strobe 
accompanying the 1st byte triggers a 
delay oneshot which, after allowing 
more than enough time for the block 
transmission, triggers a reset oneshot 
which clears the remote address 
counter, the 74160. This insures that 
the next block of data will be routed 
to the correct device in turn. 

The remote address counter sup- 
plies a 4-bit count to the 4-line-to-16- 
line data selector, the 74154. As the 



TYPICAL 
OF EIGHT 



»o 



IOWC-ADRs| ^> 




Number 


Type 


+ 5V Gn 


IC1 


7406 


14 7 


IC2 


7404 


14 7 


IC3 


74123 


SEE FIGURE 


IC4 


74160 


16 8 


IC5 


74154 


24 12 



Figure 1: The transmission circuitry is divided into 2 parts, the data transmission (DO through D7) and the address. The address is 
decoded by a counter which determines which 1 of 16 devices is being used. The write strobe accompanying the data triggers a delay 
oneshot (IC3a) which triggers a reset oneshot (IC3b) which clears IC5, the remote address counter. 



196 September 1979 © BYTE Publications Inc 



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BYTE September 1979 197 



74160 advances its count on the rising 
edge of its clock, it will initially 
supply address to the 74154 until 
the trailing edge of the negative going 
I/O write strobe. This same strobe is 
the "data" supplied to the 74154, and 
so will appear on each of the outputs 
of the 74154 in turn. This constitutes 
the 16 remote addresses. 

For expansion, 1 additional counter 
stage could be used to generate "first 
16" and "second 16" control signals to 
double the number of devices. 

Driver Programs 

The example shown in figure 1 is 
for 16 devices. Every time we want to 
output a control to any one device, 
we must output all the control words. 
OUCNT is an 8080 routine designed 
to accomplish this (see listing 1). The 
calling program first loads the correct 
bit patterns into the correct buffer 
words, then sets the flag at memory 
location FLAG. This flag is used to 
prevent needless outputting of the 
controls. In a complex control pro- 
gram, many segments of the oper- 
ating system may need to change the 
state of the devices at irregular inter- 
vals. In such an implementation there 
will be a fixed program cycle, with 
many tasks called in turn to perform 
their functions. At some point in the 
cycle, time will be allotted to output 
our controls. If no program segments 
or tasks have called for any change in 
the controls, it is not necessary to 
transmit them, and the flag will not 
be set. But when it is set, we will 
transmit all the controls, after clear- 
ing the flag. 

Controlling Relays 

Typical applications for this tech- 
nique might include driving remote 
displays, with 32 -decimal digits being 
transmitted, 2 per 8-bit byte. Or, as is 
shown in figure 2, 8 relays can be 
controlled by each 8-bit byte. 

The simplified schematic of figure 2 
shows a relay driver circuit capable of 
controlling 8 relays. The 8 bits of data 
are latched into the 74175s on the ris- 
ing edge of the clock, so our negative 
going strobe can be used as is. If lat- 
ches such as the earlier 7475 are used, 
the strobe would have to be inverted, 
since the output of a 7475 follows the 
input whenever the clock is high. In 
either case, any relay whose corres- 
ponding bit is not changed will re- 
main in the previous state, as its cor- 



;OUTPUT CONTROLS 


CONTR 


EQU 


OUCNT: 


LDA 




AN I 




RZ 




MVI 




STA 




LXI 




MVI 


OUCN1: 


MOV 




OUT 




INX 




DCR 




JNZ 




RET 


FLAG: 


DB 


BUFFER: 


DS 



OUTPUT PORT ADDRESS 



FLAG 


;NEED ACTION? 


OFFH 






;NO, RETURN 


A,00 


;YES, CLEAR FLAG 


FLAG 




H.BUFFR 


;GET CONTROL BUFFER ADDRESS 


O0FH 


;SET COUNTER 


A,M 


;GET CONTROL DATA BYTE 


CONTR 




H 


INCREMENT ADDRESS 


C 


;DECREMENT COUNTER 


OUCN1 


;CONTINUE IF NOT DONE 




;ELSE, RETURN 





;ACTION FLAG 


OFH 


;CONTROL BUFFER 



Listing 1: 8080 assembler routine to output control signals to 1 of 16 devices. CONTR is 
equated with the desired output port address. 



responding latch is reloaded with the 
same data as before. (The type of 
NPN driver transistor will have to be 
selected to match the current and 
voltage requirements of the particular 
relay used.) 

Relay Control Program 

Obviously, if we need to control 8 
relays with 1 byte, we do not want to 
change the state of all of the relays at 
the same time. This complicates the 
software required slightly. In the 8080 
program shown in listing 2, a change 
relay subroutine allows us to change 
the state of 1 relay at a time. We must 



supply the subroutine with the 
number (hexadecimal thru F) of the 
word in the buffer corresponding to 
the relay driver board, and a relay 
number (1 thru 8). We must also 
specify whether we want to turn it on 
or off. At the correct time, we put the 
word number in register C, the relay 
number in register E, and set register 
A to 1 for on, or for off, and call 
CHGRY. The next time the operating 
system calls OUCNT, only our 

+ 5V 



D0 Q> 




74175 



CLOCK 



2Q 
3Q 
4Q 



D6 O- 



13 



■o 



10 



•o 




m 



ID 
2D 
3D 
4D 



CLOCK 



74175 



IQ 
2Q 
3Q 
4Q 



■o 

■o 



■o 



15 



■o 



Figure 2: A relay driver board capable of controlling 8 relays. The state of the relay, on 
or off, is latched into the 74175 until a following strobe is received directing a change in 
state. 



198 September 1979 © BYTE Publications Inc 




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BYTE September 1979 199 



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CHANGE RELAY 
ENTER WITH: 



CONTROL WORD NUMBER IN (C) 
RELAY NUMBER IN (E) 
(A) = 1 TO TURN RELAY ON 
(A) = TO TURN RELAY OFF 



CHGRY: 


LXI 


H.BUFFR 


;GET BUFFER START ADDRESS 




MVI 


B,0 


;ADD WORD NUMBER 




DAD 


B 






ANI 


0FFH 


;TURN ON OR OFF? 




JZ 


OFF 




CHGR1: 


DCR 


E 


TURN IT ON 




JZ 


CHGR2 


;SHIFTBITTO RELAY 




RLC 




; POSITION 




JMP 


CHGR1 




CHGR2: 


ORA 


M 


TURN THIS ONE ON 




MOV 


M,A 




CHGR3: 


MVI 


A.0FFH 


;SET CONTROL FLAG 




STA 


FLAG 






RET 




;AND RETURN 


OFF: 


MVI 


A.0FEH 


TURN RELAY OFF! 


OFF1: 


DCR 


E 


;FORM MASK WORD 




JZ 


OFF2 


;SHIFT "HOLE" TO 




RLC 




; RELAY POSITION 




JMP 


OFF1 




OFF2: 


ANA 


M 


TURN THIS ONE OFF 




MOV 


M,A 






JMP 


CHGR3 


;AND RETURN 



Listing 2: This 8080 routine allows a state change for only 1 relay in a set of 8 instead of 
changing all relays at once. 



INITIALIZATION SUBROUTINE 



IN IT; 


MVI 


A,00 




OUT 


CONTR 




MVI 


A.14H 


INIT1: 


LXI 


H.BUFFR 




MVI 


C0FH 


INIT2: 


MVI 


M,00 




INX 


H 




DCR 


C 




JNZ 


INIT2 




DCR 


A 




JNZ 


INIT1 




CALL 


OUCNT 




RET 





;CLEAR REMOTE ADDRESS 
; COUNTER 
;CLEAR BUFFER AND 
; DELAY ROUTINE 
;LOOPTIME IS 250 USEC 
; SO DO IT 20 TIMES 

TO ALLOW RESET 

; OF REMOTE ADDRESS, 



THEN OUTPUT ALL ZEROS 
;AND RETURN 



Listing 3: Initialization routine to clear the address counter, buffer, and outputs all 0s to 
devices connected to system. 



selected relay will change state, even 
though all the controls are output. 

Error Free Operation 

To insure that all controls have 
been received correctly, some sort of 
feedback to the computer can be pro- 
vided. In actual practice this is usual- 
ly unnecessary, but if it must be 
implemented, there are several pos- 
sible techniques. 

First, 74180 parity generator and 
checkers could be used to generate a 
parity bit on the transmit end, and 
check it on the receive end, sending 
back an interrupt if any word re- 
ceived is in error. This would add 
only 2 more signal conductors to the 
9 already in the cable. Additionally, 
at the end of the delay oneshot time 
(and before the reset occurs), the 
remote address counter can be tested 



to insure that it has reached the all Is 
state. A count error signal can be 
ORed with the parity error signal to 
produce a single interrupt in case 
either error should occur. The oper- 
ating system can then try the 
transmission again, or at least indi- 
cate its existence. 

System Initialization 

Since, upon initial application of 
power, the states of the latches and 
the 74160 counter will be indeter- 
minate, the initializing subroutine of 
listing 3 should be called at power on 
and reset times. This will clear the 
address counter, the buffer, and out- 
put all 0s to all devices. 

I hope this short discussion of out- 
put port techniques will help readers 
to understand how the computer can 
be interfaced to the real world. ■ 



200 September 1979 © BYTE Publications Inc 



Expansive 
but not expensive 

MicroAge introduces for Horizon 
and Alpha Micro Systems, the most 
powerful Hard Disk Units You've 
Ever Seen. 



Welcome to "Hard" Times: a new 
age of hard disk cartridge drives 
for Horizon and Alpha Micro . . . 
so powerful, so reliable, so 
economical, you've never seen 
anything like it. Fast, easy and 
versatile: the revolutionary new 
Fujitsu M2201 with 40 
(formatted) megabytes of 
storage . . . and the dynamic CDC 
Phoenix with 27 (formatted) 
megabytes. Both are operated 
with North Star and Alpha Micro 
commands. Added capacity 
means the ability to fully utilize 
the complete range of software 
and capabilities of North Star 
Horizon and Alpha Micro 
mainframes. 

But their family interface 
compatibility is not all that's 
expansive. Speed and economy 
are impressive, too. Super-fast 
access time means no waiting for 
command execution . . . easy 
handling of large files. And the 
price? Unbelievably low for this 
much flexibility, power, speed 
and capacity. And the low price 
includes the hard disk drive, 
S-100 controller, software 
interface, cords and disk pack. 




Fujitsu M2201 Cartridge 
Module Drive 

50 megabyte storage 
(40 formatted) 



Exclusively from MicroAge 



CDC Phoenix Cartridge 
Module Drive 

32 megabyte storage 
(27 formatted) 



Either. 

$9995.00 

Includes drive, S-100 controller, 
software interface and disk pack. 



Ask your dealer about Hard Times — the Fujitsu M2201 and CDC Phoenix drives from MicroAge. Available to 
qualified dealers and OEM's. If a dealer is not available in your area, call 800-528-1415. 



Circle 212 on inquiry card. 



BYTE September 1979 



201 



Text continued from page 6: 

The scope of the new homebrew design has now 
expanded to include relatively high-speed serial RS-232C 
communications among the homebrew node, the 
Western Digital P-engine, the Able/60-Synclavier, and 
other computers from time to time. I intend to use RS- 
232C at 19.2 K bps as the communications discipline, 
primarily for its universality. Today one can get almost 
any computer with a standard 25-pin D connector set up 
for the RS-232C discipline, at speeds ranging from a 
lethargic 110 bps to a maximum of 19.2 K bps. This 
upper-limit of speed is not exceptionally fast (about 
1800 bytes per second is the equivalent in a useful mea- 
sure), but the existence of these standard signal levels and 
standard connectors argues for this kind of approach. 

The diagram of figure 1 shows how the overall concep- 
tion of the system stands at present. The homebrew 6809 
simultaneously provides a facility to directly execute 



Figure 1: How the 6809 homebrew computer fits into a bigger 
system. The new 6809 computer will serve as a central com- 
munications node for multiple computers involved in this per- 
sonal system. At present 2 complete computer systems are 
involved, with serial communications via the 6809 node, which 
is the subject of this homebrewing series. The Able/60 has 
several specialized peripherals which will be used for personal 
research purposes, such as, high-speed 16 channel analog-to- 
digital input conversion and a real-time clock with 1 fis reso- 
lution. In this diagram, mass storage equipment is not shown, 
but it is a part of each computer: the Able/60 computer includes 
2 5-inch floppy drives, and 2 full-size floppy drives as its mass 
storage complement. The P-Engine machine includes 2 double 
density, standard-size floppy disk drives. 



6809 code for experimental purposes, and a more per- 
manently useful function of a common communications 
node which can be the subject of various serial com- 
munications strategies relative to the other processors. 

Lest readers wonder, this is and remains a personal 
computer. It is true that the system is getting a bit large 
for one person to operate all of the terminal and music 
keyboards simultaneously, yet it resides in my home 
along with various other facilities of the complete com- 
puter experimenter: electronics shop, woodworking 
shop, and the beginnings of a machine shop. 

This expanded conception of function for the home- 
brew 6809 barely changes the hardware design details 
originally conceived. The computer will have 16 K bytes 
of memory to start, several terminal ports, several 
parallel ports, and space for 4 K bytes of ultraviolet, 
erasable read-only memory. The read-only memory will 
contain the implementation of low-level, communi- 
cations-monitor software and key parts of a reverse- 
polish notation, stack-oriented, threaded interpretive 
language. Remember that the conception of a homebrew 
or commercial system made of modular components can 
change considerably in detail as a result of time and 
resources available. 

As the system design develops from this initial inten- 
tion, its actual detail may prove inconsistent with what I 
have conjectured thus far. Recognizing this starting 
point, I invite readers to follow in on a guided tour of the 
current state of my thinking about this new, homebrew, 
microprocessor system project. Let's see how the central 
processor bus design comes out, what logic blocks will be 
required, and let's have some preliminary thoughts on the 



ORGAN MANUALS 






TO STEREO 



MANUAL 
AU0IO 
MIXING 
SYSTEM 



TO 16 MUSIC 



CHANNELS 
(PREMIXED TO 
STEREO) 



REAL TIME CLOCK 
ADC'S ■ 16 CHANNELS 

PARALLEL I/O SERIAL I/O 



SYNCLAVIER 



NEW ENGLAND 
DIGITAL 



WESTER DIGITAL 



•ENGINE 
MACHINE 



0-8 
MUSIC 

CHANNELS 
(PREMIXED 
TO STEREO) 



SPARE SERIAL CHANNELS 



RS-232C 



HOMEBREW 6B09 - COMMUNICATIONS NODE 



ALF PRODUCTS 




FUTURE 

COLOR GRAPHICS 

DISPLAY 

PROCESSOR 



MARANTZ-SUPERSCOPE 
"VORSETZER" 



STEINWAY PIANO OUTPUT 



202 September 1979 © BYTE Publications lnc 



COME TO 




AST 

INESS 



HYNES AUDITORIUM, PRUDENTIAL CENTER, BOSTON 



Interested In Personal Computers? 

This is the place for you! You'll meet and talk with 
hundreds of manufacturers, distributors and retailers . . . 
all showcasing their new 1980 Micro, Mini and Small 
Computer Systems. 

You'll see them all. ..Radio Shack, Pet, RCA, 
Compucolor, Heathkit...you name it! All the major 
terminal and peripheral companies too, plus software 
developers magazine editors and book publishers. Yes, 
it'll be the largest showing of personal computer 
hardware, software and services ever assembled in 
the Northeast! 

You'll be enthralled, entertained and educated. You'll 
see computer art, graphics and animation. You'll hear 
computer synthesized music, watch computerized 
amusements, play electronic and video games wl 

and attend scores of free tech talks and 
briefings given by internationally 
recognized speakers. And you may 
win a free computer given away 
as a door prize! Don't miss the 
largest gathering of computers 
and computerists! No 
pre-registration necessary. 
Tickets available at the door. 
Adult admission $5.00. 



Produced by Northeast Expositions, P.O. Box 




Interested In Business Systems? 

Interested in Business Systems? This will be your one 
opportunity to see all of the Mini, Micro and Moderate 
Sized Computer Systems under one roof. Your 
attendance at this show is a must if you, or your 
company, are contemplating the purchase of any type 
of computer or office equipment. 

You'll see them all. ..the big ( and small) names in 
computers, data and word processing eqiupment, 
peripherals and software. You'll attend dozens of free, 
easily-understood briefings on how computers can 
help you in your business or profession. '* 
So if you're considering a computer or computer- 
related service. ..starting yourown computer 
business or changing your job within the 
mputer industry. ..or if you'd just like to learn 
more about computers as they relate to 
your personal life and to your 
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the entire family, It's a fun- 
filled educational experience. 
No pre-registration necessary. 
Tickets available at the door. 
Adult admission five dollars. 



lage, MA 02147 (617) 522-4467 



Circle 284 on inquiry card. 



BYTE September 1979 203 



Circle 401 on inquiry card. 



Z S - SYSTEMS 




64K RAM BOARD 



The Z S -SYSTEMS 64K RAM 
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— 2 or 4MHz operation 
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— Memory disable 

FLOPPY DISK 
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Handles with no modification 
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Run with 2 or 4 MHz CPU 



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Available from stock 

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Price of one $649.00 

PC board only $59.00 

With 16K RAM $359.00 

Plus shipping charges 




Use CP/M Disk Operating System 

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Price oi one $245.00 



SEND FOR FREE INFORMATION 

6 months warranty on our boards with norma/ use 

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16K STATIC RAM 




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Assembled, Tested and Guaranteed 



Static TMS 4044 or equivalent - Fully Static 4Kx1 Memory Chips 
for full DMA capability, no tricky timing problems. 

Fully S-100 Bus Compatible - All lines fully buffered. Dip Switch 
Addressable in two8K block, 4K increments. Write Protectable 
in 2 blocks, Memory Disable using Phantom, Battery back up 
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Bank Select - Using output port 40H (Cromemco software 
compatible)-addressable to 512KB of Ram for time share or 
Memory Overlap, also has alternate ports 80 H, COH. 

Guaranteed - Parts and labor for one year. You may return the 
undamaged board within 10 days for a full refund. 

Orders - You may phone for Visa, MC, COD ($4 handling charges 
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partitioning of the system into cards within the 6-slot 
backplane previously described. 

Designing The Logic Of The System 

The task at hand is to design the central processor card 
for this homebrew computer. This is the starting point for 
the design of the whole system. Detail choices made in 
the processor card's arrangement impact every other card 
designed for the system. 

We know, that the system must have 16 address lines 
and 8 data lines because it uses a 6809 processor architec- 
ture, and simplicity dictates avoidance of extra logic for 
memory paging schemes. But which 24 lines of the 40 re- 
maining in the backplane bus should be committed to 
which particular uses? Every board in the system must be 
consistent with this detail choice. The choice is made 
trival by the fact that, except for aesthetic and symmetry 
reasons explained below, one backplane line is as good as 
the next. 

If we were building a computer consistent with plug 
compatible backplane bus designs such as the SS-50 of 
Southwest Technical Products Corporation, or the In- 
stitute of Electronic and Electrical Engineers (IEEE) S-100 
standard bus, these choices would be crucial to that goal 
of plug compatibility. However, a homebrew system is a 
homebrew system, so our plug compatibility will be at 
the level of integrated circuits, not at the level of 
backplane buses. 

Designing The Logic Of The System — 
Backplane Setup 

As noted in the July BYTE page 194, the power supply 
wiring of the backplane has been committed to the outer- 
most pins of the sockets. The assignment of power supply 
pins used 32 of the 72 pins available, in order to take 
advantage of the heavy copper wires of the buses. The 
power supply wiring commitments were made consistent 
with a symmetry principle: if a board should be 
inadvertently rotated 180 degrees and plugged in, all 
power buses will map into identical power buses. The 
outermost power bus is the — 12 V analog power bus. 
Proceeding inward, the next symmetric pair will be used 
for the +12 V analog power; the next pair of buses is for 
the +5 V main logic power supply. The innermost power 
buses are the central system ground buses. In table 1, a 
listing of backplane bus connections, these initial 
assignments of power pins are shown in shade (a). 

The power supplies used in building this system are 
provided by relatively inexpensive modular building 
blocks from James Electronics. The +5 V logic power is 
provided by a single regulated supply rated at 6 A. The 2 
analog supply voltages are provided by separate modules 
rated at 1 A. In the photographs of the physical hard- 
ware, these modules are shown as mounted, prior to 
wiring. 

In the design of the backplane bus once the power sup- 
ply committments have been made, the next items to con- 
sider are the data and address lines. Continuing the pro- 
cess of symmetrical allocation, the 16 address lines and 8 
data lines should be assigned to bus pins in such a manner 
that if a card is rotated, data lines will map into data 
lines, and address lines will map into address lines. The 
address lines are split into 2 groups of 8 connections on 
either side of the symmetry axis. The data lines are 



204 September 1979 © BYTE Publications Inc Circle 331 on inquiry card. 



ONE PACKAGE DOES IT ALL 

Includes these Application Programs . . . 

Sales Activity, Inventory, Payables, Receivables, Check/Expense Register, 
Library Functions, Mailing Labels, Appointments, Client/Patient Records 



'MICRO-AP MICRO-AP MICRO-AP MICRO- 
AP MICRO-AP MICRO-AP MICRO-AP MICR 
P MICRO-AP MICRO-AP MICRO-AP MICRO- 
RO-AP MICRO-AP MICRO-AP MICRO-AP MICR 
O-AP MICRO-AP MICRO-AP MICRO-AP MICRO- 
ICRO-AP MICRO-AP MICRO-AP MICRO-AP MICR 
XRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO- 
iP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICR 
MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO- 
i-AP MICRO-A P MICRO-AP MICRO-AP MICRO-AP MICR 
~|MICRO-AP MICRO-AP MICRO-AP MICRO- 
mp MICRO-AP MICRO-AP MICRO-AP MICR 
■MICRO-AP MICRO-AP MICRO-AP MICRO- 
|\P MICRO-AP MICRO-AP MICRO-AP MICR 
IMICRO-AP MICRO-AP MICRO-AP MICRO- 
IvP MICRO-AP MICRO-AP MICRO-AP MICR 




AP MICRO-AP "BB^^m ^— ^"""Bi BOAP MICRO-AP Ml 

RO-AP MICRO-ARM B KRO-AP MICRO-AP t 

AP MICRO-AP mB ■ Bj^KffwjH Bo-AP MICRO-AP Ml 

RO-AP MICRO-ARM BcRO-AP MICRO-AP > 

AP MICRO-AP mB H___^^^B|a Bo-AP MICRO-AP Ml 

RO-AP MICRO-ARM BdRO-AP MICRO-AP H 

AP MICRO-AP mB Bo-AP MICRO-AP Ml 

RO-AP MICRO-ARM BpRO-AP MICRO-AP t 

AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP Ml 
RO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP K 
AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP Ml 
RO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP MICRO-AP * 



RANDOM, MULTI-KEY RECORD RETRIEVAL under CP/M, CDOS, IMDOS, ADOS 



SELECTOR Ml ALLOWS 
INSTANT RECALL OF ANY 
RECORD USING ANY IN- 
FORMATION ITEM IN THE 
RECORD. That statement 
deserves re-reading, be- 
cause that ability makes 
SELECTOR III the most 
powerful Date Base Man- 
agement System in micro- 
computers today! 

With SELECTOR III 

you can... 

• define a record format, 
assign retrieval keys, and 
begin entering data in min- 
utes. 

• create sorted pointers to 
records matching your spe- 
cif or range of requirements. 

Circle 213 on inquiry card. 



• automatically generate 
reports with control-break 
summaries and unlimited 
variety. 

an application on- 
hours instead of 



• bring 
line in 
months 



SELECTOR III comes com- 
plete with eight application 
programs that perform the 
tasks listed at top of page. 
And, since it's distributed in 
source code form, you can 
easily add subroutines to do 
specific computations or 
file updates. 

SELECTOR III runs under 
CBASIC Vers. 1 or 2, and is 
priced at $295. SELECTOR 



III-C2 is dedicated to Vers. 2 
only, runs about twice as 
fast, and costs $345. 

Both systems are available in 
a variety of CP/M, diskette 
size and density formats 
including IBM 8"; North Star; 
Micropolis; TRS-80; Pro- 
cessor Tech Helios II; Altair; 
iCOM; Dynabyte; Imsai; 
and others. 



| Available from computer stores nationwide: I 

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Or order direct from ■ 

MICRO-AP 

■ 9807 Davona Drive, San Ramon, CA 94583 I 
(415) 828-6697 | 



I 



BYTE September 1979 205 



allocated into 2 groups of 4 connections. Continuing the 
listing of the backplane connections in table 1, these 
assignments of 24 address and data pins are shown in 
shade (b). At this stage in the allocation of logical signals 
to the bus, 24 of 40 available pins have been used, leaving 
16 pins still to be determined. 

The next item to consider is the set of lines which con- 



(-12V)-- 

-- (-12 V)-- 

= = = = =(+12 V) = 
= = = = =( + 12 V) = 



1 3 : : ; : = A4 X:X : : : x : x : : : : : : : : : x : x : x : x : : 

1 4 •:•;' = A5'+:;:;:;:+:;:+:;:;x;:;:;:;:;:;:;:;:; 

1 6 :•:• =.A7 ;x+:::;:;x::::::::::::::::;::::::x; 

1 7 = RESET 

18 = NMI 

19 = unassigned 

20 = ENABLE 

21 = 14 •: 

22 d 15 j; 

23 = 16 |: 

24 = 17 : : 



25 : : X=.D4'. 

26 :•:>= D5: 



(a) 



(b) = 



72 
71 
70 
69 



+ + + + + + + MAIN PWR ( + 5 V) + + + + + + + 68 

+ + + + + + + MAIN PWR ( + 5 V) + + + + + + + 67 

GROUND (0 V) 66 

GROUND (0 V) 65 



9 : x = ao y^v'xjxoxlx^xjxjxlxlxjxjxjxjx '■:'■: 64 

10 8'= Ai'Sx'xxS^ di ='•:•: 63 



1 1 :•:■ = . A2 i&SS&S:^^ R? f. x : 62 

1 2 x : '= A3 "^S^:^SS^SS^S:§SSSSS:^ D3 =' : : : : 61 



10 = 60 

11 = 59 

12 = 58 

13 = 57 
QENABLE = 56 

unassigned = 55 

IRQ = 54 

RW = 53 

^i^x+x "as '= *: 52 

x+x'+x'l "A9^=:x 51 

;:-:-:jSjij:-:Aio =;:•: 50 

:•*:*:** Ali'=: : : : 49 



: A12 = : x 48 
: A13 = :>: 47 



27 :x:=.P6;xjxj:v:x:;:j:vx;:j:v:x:v:;:v:v:x:x:xXv:x:;:;x;AH = ::j: 46 

28 :*:= .^J:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-S^ .=.:•:: 45 

29 GROUND (O V) 44 

30 GROUND (0 V) 43 

31 + + + + + + + MAIN PWR ( + 5 V) +++ + + + + 42 

32 + + + + + + +MAIN PWR ( + 5 V)+ + + + + + + 41 

33 = = = = = = = = =(+12 v)= = = = = = = = = 40 

34 = = = = = = = = =(+ 12 V)= = = = = = = = = 39 

35 - ( - 1 2 V) 38 

36 ( - 1 2 V) 37 



(c) = 



nect the central processor to the external world. These 
lines are the essential timing and control signals which 
define the discipline of the bidirectional 8-bit bus used by 
the microprocessor. In the specifications of the 6809, the 
following signals are defined which have relevance to the 
outside world: 

• RW = Read versus Write bus direction relative to 
the processor. 

• ENABLE = Clock ouput ("Phi 2") of processor. 

• QENABLE = Quadrature clock of processor. 

• RESET = system reset line to processor and all 
peripherals. 

• MRDY = memory-ready line, for use with slow 
memory devices. 

• BREQ = bus request for direct memory access 
(DMA). 

• BA = bus available. 

• BS = bus status. 

• FIRQ = fast interrupt request. 

• IRQ = interrupt request. 

• NMI = nonmaskable interrupt request. 

The simplest and most direct way to deal with these 11 
signal lines would be to bring them out to the backplane. 
But do we really need all these signal lines in this pro- 
cessor? Might it be more useful to commit a majority of 
the remaining 16 lines to interrupt activities, rather than 
having nonessential copies of the lines coming from the 
processor circuit? For example, we may prefer to incor- 
porate 8 separate interrupt lines in order that each of a 
possible 8 peripheral devices could have a dedicated line. 
If this is to be accomplished, then the total commitment 
of noninterrupt lines to the backplane must be 8 lines 
instead of the mixed selection of 3 interrupt lines and 8 
signal lines shown above. How can we modify this set of 
backplane signals given the limitations and purposes of 
this particular design? 

First, remember that this application is a simple and 
limited one in which no direct-memory access is being 
implemented, and that all memory will be fast enough to 
drive the processor at full speed. Given this requirement, 
the 2 signals memory ready (MRDY) and bus request 
(BREQ) can be removed from the set seen by the external 
world beyond the processor card. We have thus reduced 
the backplane line count to 9 lines, nearly enough to 
allow 8 distinct interrupt lines. 

The next items to question are the bus available (BA) 
and bus status (BS) signals. These are used to decode 1 of 
4 possible states: normal operation, interrupt acknow- 
ledge, synchronization acknowledge, and bus grant (halt 
acknowledge). Of these, the limited goals of the present 

Table 1: An allocation of backplane signals. As described in the 
text, this backplane signal set provides for 8 bidirectional data 
lines, 16 address lines, 8 individual fast interrupt lines used with 
a (slow) software polled strategy, 2 direct interrupt lines, and 4 
essential timing signals for the 6809 and its relationship with the 
external world. The assignment of these lines is kept sym- 
metrical, so that while the processor may not work if any board 
in the system is inadvertantly plugged in the wrong way, no 
major conflicts will occur that could damage a gate or buffer. 
The shades indicate stages in the backplane allocation process 
described in the text: (a) pins are the power connections; (b) pins 
are the address and data connections; (c) pins are the 16 lines 
allocated to processor control signals and interrupts. 



206 September 1979 © BYTE Publications Inc 



FALL 1979 



0001010111 110100010101 110101000000010000101 11110100010101011 11 10100010101110 

JAM€S MARTIN 



S€MINAR 



00010101 1 1 1 10100010101 1 1010100000001000010101 1 1 1 10100010101 1 1010100000001000 




Future Strategy, 
Management, 

& Design for: 

■ Distributed Processing 

■ Data Base 

■ Networks 

■ Corporate Strategy 



Washington, D.C. October 15 

Los Angeles October 22-26 

Boston November 5-9 

Chicago November 26-30 

Seminar Fee: $1150.00 

■•- • .. _ __. : . 



0001010111110100010101110101000000010000101011111010001010111010100000001000 



CALL OR WRITE: 

(213)476-9747 



Circle 364 on inquiry card. 



P.O. BOX 49765, LOS ANGELES, CA.90049 (213)476-9747 

BYTE September 1979 207 




WANTED: 

ASSISTANT 
EDITOR 



?n 



Job Opportunity 



onComputing , BYTE's companion 
magazine, is growing rapidly. We have an 
immediate opening for the job of assistant 
editor of onComputing , a McGraw-Hill d 
publication. This creative opportunity 
offers the potential for growth in the,, 
exciting world of publishing. 

Candidates for this position 
should have a firm grounding in 
personal computer hardware and 
software, and should have the 
ability to write and edit clearly and 
accurately. A technical degree and 
some journalism experience are 
desirable but not mandatory. «C;._ 
onComputing covers the world of personal computing, but is 
written in a less technical style than BYTE. It is aimed at the 
beginner, professional person, student, and anyone interested in 
learning more about personal computers. 

onComputing is located in Peterborough NH, the heart of the 
southern New Hampshire vacation region. Conveniently located 
90 minutes from Boston, Peterborough offers the benefits of a 
wide variety of cultural activities, plus the peaceful seclusion of 
the country. 

If this position sounds interesting, we'd lixe to hear from you. 
Send your resume in confidence to Chris Morgan, Editor-in-Chief, 
onComputing , 70 Main St, Peterborough NH 03458, or call (603) 
924-7217. 

Time is of the essencel 




system make the only externally relevant state "normal 
operation" if we can confine interrupt handling logic to 
the processor card. Can this be done? The answer is 
"yes", if we define fixed read-only memory vectors for all 
interrupts, and eliminate the need to decode interrupt 
acknowledge externally for purposes of altering the inter- 
rupt vector locations. Thus the backplane signal require- 
ments have been further reduced to 7 lines, still allowing 
the 3 originial interrupt lines to come out to the external 
world off the central processor card. 

Now let's examine the interrupt handling capabilities of 
the processor. Of the 3 available interrupts, the fast inter- 
rupt is the most general. The reason for this is that it only 
stacks away the essentials of the processor state when 
acknowledging the interruption with a branch through 
the FIRQ vector location, hexadecimal address FFF6. 
These essentials are the condition code, and the return 
address. In contrast, the NMI and IRQ interrupts always 
stack away the entire current contents of the central pro- 
cessor's set of registers. If we use the FIRQ signal for most 
interrupt activity, then, when speed is needed, only those 
registers which are used by the interrupt routine can be 
stacked away using the multiple register push and pull 
instructions. If the operation of the NMI or IRQ (ie: com- 
plete protection) is required, the multiple register opera- 
tion of push and pull can be extended to cover all the pro- 
cessor registers using the proper "post-byte" which selects 
registers. 

What about devoting the FIRQ interrupt input to 8 dif- 
ferent possible sources, using a concept of a software- 
polled flag register and a parallel input port to prioritize 
"who called"? This elminates 1 more line from the 
original backplane signal requirements, while adding 8 
interrupt lines labeled 10 through 17. We keep the NMI 
and IRQ lines available for truely high-priority interrupt 
signals which must go in directly without much software 
decoding. Our result then is the final backplane signal set 
listed in table 1, with this last set of additions shown in 
shade (c). Two lines are left uncommitted at this stage, in 
case an essential signal concept is omitted. One or more 
interrupt lines (10 through 17) can be sacrificed, if more 
than 2 lines must be added due to some shortcomings. 

With this general discussion of the system's backplane 
complete, I will continue these notes next month with a 
more detailed sketch of the system's most important card: 
the central processor module. Following this design 
discussion, the final installment on the processor module 
will be a short description of the detailed schematic as I 
wire it. ■ 



Articles Policy 

BYTE is continually seeking quality manuscripts written by indi- 
viduals who are applying personal computer systems, designing 
such systems, or who have knowledge which will prove useful to 
our readers. For a more formal description of procedures and 
requirements, potential authors should send a large (9 by 12 inch, 
30.5 by 22.8 cm), self-addressed envelope, with 28 cents US postage 
affixed, to BYTE Author's Guide, 70 Main St, Peterborough NH 
03458. 

Articles which are accepted are purchased with a rate of up to $50 
per magazine page, based on technical quality and suitability for 
BYTE's readership. Each month, the authors of the two leading 
articles in the reader poll (BYTE's Ongoing Monitor Box or 
"BOMB") are presented with bonus checks of $100 and $50. Unso- 
licited materials should be accompanied by full name and address, 
as well as return postage. 



208 September 1979 © BYTE Publications In 




Model DMB-6400 Series dynamic 64k byte RAMS incorporate the 
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increments. 

• Eight (8) 64k byte banks of mem- 
ory per output port. 



Model DM-6400 Series dynamic 64k memory boards feature IEEE 
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• Memory selectable and deselec- • 25 MHz on board crystal oscillator 

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DMB-6400 and DM-6400 Common Features: 



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• Reliable, expandable memories. 



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U.K. & EUROPEAN REPRESENTATIVE: 

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TEL: 625581 



MEASUREMENT 

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incorporated 

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Telephone: 714/633-4460 



Circle 215 on inquiry card. 



BYTE September 1979 209 



Circle 133 on inquiry card. 



Circle 198 on inquiry card. 



Belais' Master Index to Computer Programs 

in BASIC Gives You Access to $14,836.14 
Worth of Computer Programs for Just $7.95! 

Now Available Off-The-Shelf 



You paid hundreds or even Ihousands of dollars 
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dawning on you that a $1 ,000 computer with no 
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But computer programs cost money. In a recent 
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Ihe average price was found to be $27.94. What a 
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Belais' Master Index gives reviews of 531 pro- 
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computer magazines— programs (hat you can 
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This large 8 1 /; x 11, 192-page directory is 
packed with information. This is not just a simple 
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Each BMI review is complete — it has everything 
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Source information shows you where the program 
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We don't provide the program listings them- 
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You don't have to be a programming wizard to 
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Then again, there's always MONEY. Maybe you 
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To order, write you name, address, and the 
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Send your order to Falcon Publishing. 
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We absolutely guarantee you'll find Belais' 
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you paid. You can't lose, so order NOW? 



TRS-80 SOFTWARE 
32K with 2 DISK DRIVES 

PAYROLL SYSTEM $235 

Includes: a) File Maintenance 

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d) Payroll Register 

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f) Write Other Checks 

Handles up to 300 employees per diskette. 
Automatically calculates FICA, FED. TAX, 
UNEMPLOYMENT and much more. 

ALSO AVAILABLE 

ACCOUNTS RECEIVABLE $1 95 

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INVENTORY CONTROL with 

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Now learn the 

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Enjoy the challenge and 
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National Technical School's Microcomputer Division offers three such 
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Find out more about these valuable NTS Microcomputer Courses, Send today 
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No obligation. No salesman will call. Approved for veteran training. 




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SCHOOLS 



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TRS-80 FUN GAMES 
at NEW LOW COST 

CRAPS - all types play - no player limit $6.95 

BIG SIX ■ 40 different number combo $5.95 

BIORYTHM - different from any others $5.95 

PERPETUAL CALENDAR from Christ to infinity $4.95 

SAVE $4.80 - 

Order all 4 Programs for only $19.00 

BLANK C ID CASSETTES - Highest Quality 1-5 

$1.30 ea; 6 10 $1.15 ea; 11-20 $1.05 ea; 

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Please ship the following: 



NATIONAL TECHNICAL SCHOOLS 

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Please rush your FREE 65-page color catalog 

Name 



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D CRAPS $6.95 

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D ALL 4 PROGRAMS $19.00 
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I □ Check if interested in G.I. Bill information. 

| □ Check il interested ONLY in classroom training in Los Angeles 

L..«.. 

210 BYTE September 1979 



Circle 279 on inquiry card. 



Complete money back guarantee. No questions. Personal checks accepted. We 
trust you. All shipments made in 10 days. 



Circle 101 on inquiry card. 



Circle 287 on inquiry card. 



# Omikron transforms TRS-80* 
into a powerful business system. 



STANDARD DRIVES 8" Drives give you 5 
times the speed and 3 times the storage of 
your mini drives! Our system provides a 
standard Shugart interface so you can use 
either your 8" drives or ours. Omikron 
drives are enclosed in an attractive metal 
cabinet, and include a power supply. 

SOFTWARE CP/M* is the most popular 
operating system for microcomputers. But 
many high-level languages and advanced 
business programs cannot run with the 
special CP/M* designed exclusively for the 
TRS-80* The Omikron MAPPER with 
standard CP/M* allows you to expand your 
software capability to go beyond the few 
available TRS-80* compatible packages. 
TRS-80* with MAPPER 
out-performs systems 
costing $1000 
more 



The MAPPER I and MAPPER II are plug- 
in modules. They don't require any circuit 
changes, are easy to install, and they don't 
interfere with the normal operation of your 
TRS-80? All your original software, includ- 
ing Level III BASIC will still run properly. 
Omikron products require 16KL II BASIC 
and the TRS-80* Expansion Interface. 

• • • 

MAPPER I is a memory management unit 
which adapts your TRS-80* to run stan- 
dard CP/M* Versions for both 5" and 8" 
drives are available. The package includes 
CP/M* software on 5" or 8" diskette, and 
documentation. 5" unit, $169. 8" unit, with 
adapter cable, $199. 



MAPPER II includes the MAPPER I pack- 
age plus a disk adapter module which 
allows both 5" and 8" drives to run on the 
same cable. Drive selection is under soft- 
ware control to permit easy file transfer 
between the drives. With cable, $249. 
CONVERSION -If you purchase MAP- 
PER I or II and plan to use only mini- 
drives, Omikron will transfer CP/M* files 
from 8" diskette to a 5." This allows you to 
run software previously available to only 
8" drive owners. $25 per mini-diskette. 
DRIVE - 8" drive, $849. Additional drive, 
$695. WARRANTY- 1 year on boards; 
90 days on drives. VISA/MasterCharge 
accepted. Prepaid orders given top priority. 

*CP/M is a TM of Digital 

Research. TRS-80 is 

a TM of Tandy 

Corporation. 




PROFESSIONAL 




INCOME TAX PROGRAMS 
FOR TRS-80™ 



Accountants, lawyers, tax consultants nationwide, prepared over 30,000 1978 
Federal tax returns using our system. 

Displays and fills in Form 1040 and related schedules on the screen, then 
prints out the completed forms automatically. 

Change your mind? Make an error? Correct a single entry and you have a brand 
new form with all re-computations made automatically. 

No tax system, running on any computer anywhere, has all the features of our 
professional system, and yet— 

Our base program, which does 1040 and Schedule A costs only $189.95 

And! You can add schedules for only $37.95 each, customizing your system 
to your requirements. 

CONTRACT SERVICES ASSOCIATES 

706 SOUTH EUCLID ANAHEIM, CA 92802 

TELEPHONE (714) 635-4055 

FREE CATALOG AND BROCHURE TO PROFESSIONALS 



Circle 82 on inquiry card. 



BYTE September 1979 211 



Circle 18 on inquiry card. 



Circle 327 on inquiry card. 




A specially designed SF TACTICAL BATTLE GAME for 
your PET, TRS-80 or APPLE Computer. 

The man called Sudden Smith watched the five blips on 
his screen spread out to meet the enemy. Two freighters 
converted into something like battlewagons, powerful 
but slow, and three real cruisers: the most powerful group 
of warships ever seen near the Promethean system — except 
for the Stellar Union fleet opposing them. Everyone was 
calling it Starfleet Orion, though it existed for only this 
day. It was life or death, and, after the object lesson on 
the planet Spring, everyone knew it. 

STARFLEET ORION is a complete 2 player game system 

• rule book • battle manual • cassette 

• ship control sheets • program listings 

Includes 2 programs, 22 space ship types, and 12 playtested 
scenarios. Game mechanics are extremely simple, but play 
is exciting, challenging, and rich in detail. Specify PET (8K), 
TRS-80 (Level II, 16K), or APPLE II (16K& 32K) $19.95. 

Ask your local dealer or send your check to: 

Automated Simulations 
Department Y 
P.O. Box 4232 
Mountain View, CA. 94040 

California residents please add 6% sales tax 



6800 DEVELOPMENT SOFTWARE 

An integrated applications development and execution system. 

SDOS 

All devices interrupt-driven including typehead. Provides 
device independent, byte addressable random files. Supports 
any mixture of floppy or hard disk drives up to 2.5 billion bytes. 
Sector read-ahead and buffer pool enhance application perfor- 
mance. Flexible: Currently runs on 7 manufacturers' systems, 
using 10 different drive/controllers, including mini-floppies and 
hard disk. 

BASIC COMPILER 

For speedy business applications. 10 digit BCD; random access 
to variable size records; long variable names; formatted out- 
put; if-then-else; error trapping. Field proven for over 2 years. 

EDIT 

A powerful text editor with change, delete, replace commands. 
Automatic display of modification or context changes; macro 
facilities for complex or repetitive editing. 

ASM 

2 pass conditional assembler; 32 character labels; symbol table 
dump and cross-reference; error cross-reference; extensive 
arithmetic and listing control. 

IOB 

Single-step, multiple, real time breakpoints; memory dump; 
multiple display modes. No special hardware needed. 

Over 500 pages of documentation to match this proven soft- 
ware. 

Complete package: $760.00 

Also (not including SDOS) available for SWTP, Exorcisor, SSB 
and MSI DOS. 

Write for free catalogue. Sizable distributor discounts. 

SOFTWARE DYNAMICS 

2111 W. Crescent Avenue, Suite G 

Anaheim, CA 92B04 

(714)635-4760 




TRS-80 disk software 



DISKETTE DATA BASE IDM-III 32K $49 

You can use it to maintain a data base & produce reports without any 
programming. Define tile parameters & report formats on-line. Features key 
random access, multi-keys, sort, select, field arith, audit log. Almost use up 
all 32K. 

ACCOUNT manage client accounts & account receivable. Automatic billing & 
transaction recording. Print invoices and reports. 32K req. $59. 

WORD PROCESSOR 16K $39 

Our WORD-HI is the first word processor specifically designed for TRS-80 
that uses disk storage for text. Written in BASIC. No special hardware and 
text limit. Use for letters, manuals & reports. 

MAILING LIST 16K $35 

It lets you maintain data base and produce reports & labels sorted in any 
field. Random access. 2-digit selection code used. 

INVENTORY 16K $39 

While others use inefficient sequential file, we use 9-digit alphanumeric key 
for fast on-line random access. Record has key, description, level, safety 
level, order ami, unit cost & price, annual usage, location and vendor code. 
Reports give order info, performance summary, etc. 

KEY RANDOM-ACCESS UTIL 16K $19 

Lets you access a record by specifying a key. Features hashing, blocking, 
buffering technique, auto I/O error retry, etc. 



MICRO ARCHITECT 

96 Dothan St. 
Arlington, MA 02174 



'TINY' PASCAL 
tor TRS-80® 

& NORTH STAR® 

Now you too can have Pascal! The Chung/Yuen 'Tiny' Pascal has 
been specially designed for TRS-80 & North Star owners. The full 
power & elegance of 'Tiny' Pascal is at your command. Programs 
written in 'Tiny' Pascal run at least 4 times faster than the same 
program in BASIC! 'Tiny' Pascal is also a great way to learn 
Pascal Programming, & fun too. 

The minimum system requirements are: Level II, 16K for TRS-80, 
(no disk required) & 24K for North Star (specify density). 

SOURCE TOO! 
But most important, you also get source to 'Tiny' Pascal written 
in Pascal with each purchase! You can even compile the com- 
piler! (Requires 36K for North Star systems, & 32K, Level II for 
TRS-80). You can customize your own version, or just use it the 
way it is. 

'Tiny' Pascal is a subset of Standard Pascal & includes. 
RECURSIVE PROCEDURE/FUNCTION, IF-THEN-ELSE, 
REPEAT/UNTIL, 'PEEK & POKE', WHILE, CASE, & MORE! 
(Plus full graphics for TRS-80 as well) 
Also you can save & load programs. 
You get all this & more, plus a user's manual for $40.00. 

available from: 

/mm/on 

P.O. Box 1628 
Champaign, IL 61820 
(217) 344-7596 
^ All orders pre-paid, Illinois residents add 5% sales tax 



212 BYTE September 1979 



Circle 214 on inquiry card. 



Circle 359 on inquiry card. 



Circle 102 on inquiry card. 



BYTE 

BACK ISSUES 

FOR SALE 

The following issues are available: 

1976: July 

1977: March, May thru December 

1978: February, October, December 

1979: January thru August 

Cover price for all issues thru August 1977 is 

$1.50 plus $.25 postage and handling ($3.50 total foreign). 

September '77 thru '79 issues are $2.00 plus $.50 

postage and handling ($4.00 total foreign). 

Send requests with payment to: 

BYTE Magazine 

70 Main St, Peterborough NH 03458 

Attn: Back Issues 



KITE 




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ELECTRONIC CONTROL TECHNOLOGY ( 2 od bsg-boso 



Circle 120 on inquiry card. 



BYTE September 1979 213 



What's New? 



Low Cost Computer Assisted Instruction 

APPILOT language is an Apple II ver- 
sion of the standard computer assisted 
instruction (CAI) language, PILOT. Using 
lesson files created by the APPILOT pro- 
gram editor, APPILOT creates multi- 
media learning experiences with text, 
graphics and sound. The student can in- 
teract with APPILOT using both numbers 
and words which APPILOT recognizes as 
student input. 

APPILOT conforms closely to the pro- 
posed common PILOT standard, but it 
incorporates features that fully use the 
capabilities of the Apple II computer. 
Among these features are color graphics 
commands, a musical minilanguage, and 
disk commands for lesson segmentation 
which give an effective lesson size up to 
90 K bytes. APPILOT also links to the Ap- 
ple's integer BASIC to allow full calcu- 
lation capacities. 

APPN OT is available on tape and 
disk, and is offered on Super Load tapes 
and for those Apple owners who wish to 
run prewritten APPILOT lessons. For 
$17.95 the user can execute APPILOT 
lessons on a 16 K byte Apple, using only 
tape storage. Included on the tape is the 
interpreter and a demonstration lesson 
about APPILOT. Also provided is a 
documentation manual for running 
APPILOT and for linking it with the 
MUSE APPEN-I Text Editor, which may 
be used for creating and editing 
APPILOT lessons. 

For institutions that wish to write as 
well as use APPILOT lessons, the 



CP/M Text Editor 

ED-80 is a text editor designed to 
run under CP/M and derivative operating 
systems on 8080, 8085, and Z-80 disk 
based systems. A user's manual of over 
60 pages describes both implementation 
and usage. ED-80 has a simple command 
structure patterned after the University 
of Maryland's editor for UNIVAC 1100s. 
Over 50 commands are provided, includ- 
ing forward or backward locate, change, 
and find commands; insert, delete, 
append, print, list, macro, case, scale, 
tabset, and window commands; and get 
and put commands for copying, moving, 
merging, and duplicating edit files and 
program libraries. An internal location 
counter is maintained for dis- 
playing with text, prompting for user 
input, and for line positioning. 

ED-80 provides a window approach 
to text editing that is not hardware 



APPILOT Edu-Disk converts a 32 K byte 
Apple with disk into a complete CAI 
system. The user can develop lessons, 
store them on disk, and run them with 
the APPILOT interpreter. The Edu-Disk 
comes with interactive lessons that in- 
struct the user on all aspects of the 
APPILOT CAI development system. The 
APPILOT Edu-Disk is being offered for 
$49.95 which includes a detailed 
documentation manual. For further in- 
formation, contact MUSE, 7112 Dar- 
lington Dr, Baltimore MD 21234. 
Circle 565 on inquiry card. 



Machine Language Programs for the 
PET Computer 

The SYS7171 and the SYS8181 are two 
new machine language programs for the 
PET 2001 computer. SYS7171 is a 
machine language monitor which allows 
a programmer or PET user to program in 
machine language, or in BASIC, without 
destruction of the monitor once it is 
loaded. Programs may be saved, loaded 
or rewritten yet SYS7171 remains coresi- 
dent and undisturbed. 

SYS8181 is a machine language re- 
numbering program which requires only 
1 K byte of programmable memory for 
its operation. After it is loaded, the user 
can load a BASIC program and it will be 
renumbered in seconds. 

SYS7171 sells for $29.71 and SYS8181 
is priced at $18.71. For further informa- 
tion, contact National Artificial In- 
telligence Laboratory, POB F, Mobile AL 
36601 . 

Circle 566 on inquiry card. 



Word Processing Software System 

Autoscribe is a professional word 
processing system designed for the 
business world. With Autoscribe, typed 
text appears on a video terminal screen 
as it will be printed, and corrections, 
deletions or revisions can be made in 
seconds. The finished document is typed 
at hundreds of words per minute. 
Letters, contracts and other documents 
can be produced quickly on single page 
or continuous form print-out. The ori- 
ginal data is recorded and saved on the 
user disk. Documents can be retrieved 
instantly and reprinted as needed. No 
computer language is needed. All in- 
structions are in English. Autoscribe 
software operates on Z-80 and 8080 sys- 
tems utilizing North Star disk, a Soroc 
or Hazel tine terminal and a letter quality 
printer. For further information contact 
MicroAge Wholesale, 1425 W 12th Place, 
Tempe AZ 85281. 

Circle 567 on inquiry card. 



dependent. Users may examine and edit 
data through a one line window as it 
is moved through the edit file. A window 
command allows instantaneous full 
screen displays of both the current line 
and surrounding lines, with forward 
and backward scrolling. 

Compatible with existing CP/M edit 
files, ED-80 is available on an 8-inch 
single density disk for $71. For further 
information contact Software Develop- 
ment and Training Inc, POB 4511, 
Huntsville AL 35802. 

Circle 568 on inquiry card. 



16-Digit Scientific Subroutine Package 
for Microsoft Extended and Disk BASIC 
Interpreters 

DPFUN is a comprehensive 16-digit 
precision scientific subroutine package 
written for Microsoft extended and disk 
BASIC intepreters, including TRS-80 
Level II BASIC. The 1 3 double-precision 
exponential, logarithmic, trigonometric, 
and inverse trigonometric functions pro- 
vide a valuable utility for engineering 
and scientific applications. DPFUN uses 
truncated continued fraction algorithms 
that result in easily entered code, fast 
execution, and full exploitation of the 
precision that is available in 64-bit 
binary floating-point notation. The com- 
plete set of subroutines occupies approxi- 
mately 2.5 K bytes. 

The DPFUN source code only is 
available for $10 postpaid. For further 
information contact Miken Optical Co, 
53 Abbett Av, Morristown N J 07960. 
Circle 569 on inquiry card. 



Elementary Math Tapes for TRS-80 

The Microcomputer Mathematics Pro- 
gram K-8 consists of a set of tapes for 
drill, practice and tutorial in addition, 
subtraction, multiplication, division, 
fractions, numeration and decimals for 
kindergarten through 8th grade. The 
tapes are programmed for use on a 
Radio Shack Level II BASIC TRS-80 
microcomputer and 16 K bytes modified 
memory. The teacher's manual gives an 
overview of the program, suggests ways 
to use the program, correlates the skills 
to selected mathematics texts, and pro- 
vides suggestions for individualizing 
math instruction. One set of microcom- 
puter Mathematics Program K-8 tapes in- 
cluding the teacher's manual is $995. For 
further information, contact Foundation 
for Quality Education Inc, 802 Mer- 
chants State Bank Building, 5217 Ross 
Av, Dallas TX 75206. 

Circle 570 on inquiry card. 



214 September 1979 © BYTE Publications Inc 



Circle 12 on inquiry card. 



A COMPLETELY REFURBISHED "SELECTRIC" ASCII 
TERMINAL FOR THE SMALL BUSINESSMAN OR SERIOUS HOBBYIST. 

The AJ 841 I/O terminal. 
Now available from dealers nationwide. 



Demand for our AJ 841 I/O computer terminal has 
been great. And now it's getting even greater. So call your 
local computer shop dealer right away. Supply is limited! 
You may never have another opportunity like this one to buy 
your own professional terminal. 




The A J 841 features: 

■ Choice of serial RS 232 or parallel interface 

• ASCII code 

• 14.9 cps printout 

• High quality Selectric printing 

• Heavy-duty Selectric mechanism 

• Off-line use as typewriter 

• Documentation included 

• 30-day warranty on parts and labor (details available 
on request) 

Call toll-free now 

For location of your nearest AJ dealer, call toll-free: 

800/538-9721 

California residents call 408/263-8520. 





l« 



oV.*°* 



'd 



from Computer Headware 
. . . the Self-Indexing Query System 

for your Apple II, North Star, or CP/M machine 



Distributed by: 

. Information Unlimited / 219-924-3522 
P.O. Box 8372. Merrillville, Indiana 46410 

■ Lifeboat Associates / 212-580-0082 (CP/M model only) 
2248 Broadway, Suite 34, New York City 10024 

. Structured Systems Group, Inc. / 415-547-1567 
5208 Claremont Avenue, Oakland, California 94618 





BYTE September 1979 215 



What's New? 



MISCELLANEOUS 



Computer Communication at 
Your Fingertips 




VuePoint is a touch input display 
panel that measures only V/x inches 
thick. Vuepoint's 12 line by 40 character 
flat panel also provides a unique touch 
input capability. This approach permits 
efficient and speedy operator inter- 
action using menu-driven displays. Vue- 
point's microprocessor based controller 
provides all standard smart video 
features plus the following: touch 
response in matrix or screen echo modes, 
multiple display buffers, and alternate 
character sets. Communication is by 
standard 300-19200 bps asynchronous 
RS-232 protocol. Options include wall or 
rack mount, auxiliary printer, and 128 
character ASCII keyboard. Vuepoint is 
priced at $3500. For further information, 
contact General Digital Corp, 700 Burn- 
side Av, E Hartford CT 06108. 
Circle 571 on inquiry card. 



APL/Z-80 Release 2.0 

Vanguard Systems Corp, 6812 San 
Pedro, San Antonio TX 78216 has an- 
nounced the release of version 2.0 of 
APL/Z-80, an APL interpreter for Z-80 
based microcomputers. APL/Z-80 in- 
cludes the following features: dynamic 
execution of system commands; serial 
printer support; shared variables; aux- 
ilary processor for I/O (input/output) 
ports which allows complete device 
control using defined APL functions for 
any device interfaced to the Z-80 I/O 
port; and auxilary processor implemen- 
tation of a file system featuring a dir- 
ectly indexable file having variable 



length records, each of which can be an 
APL array of arbitrary type, shape, 
and size (up to available workspace). 

A workspace containing defined 
APL/Z-80 functions, implementing each 
of the primitive functions not present 
in this version of APL/Z-80, is distri- 
buted with each system. The hardware 
required is a Z-80 processor, a disk drive, 
and either serial ASCII APL console 
terminal or ASCII keyboard and video 
display board compatible with the 
Vector Graphic Flashwriter or Processor 
Technology VDM-1. 

The end user license for use on a 
single processor is $350. 

Circle 572 on inquiry card. 



Distributed Computer System Based 
on Personal Computers 




Cluster/One is a distributed pro- 
cessing alternative to BASIC timesharing. 
The central Cluster/One unit (the Queen) 
connects to 15 personal microcomputers 
(the Drones), via a high-speed parallel 
data bus (the Clusterbus). An optional 
feature provides support for an addi- 
tional 15 Drones. Currently supported 
as Drone stations are the Apple II, 
Commodore PET 2001-8, and TRS-80. 



Programs and data files can be shared 
among the users of Cluster/One. They 
are stored on two IBM compatible eight 
inch floppy disks. Each disk holds up to 
315 K bytes of data. Disk data transfer 
rate is 250 K bits per second, managed 
by a large scale integration floppy disk 
controller chip. All data transfers arc 
cyclic redundancy checked (CRC) and 
disk writes are automatically verified. 
Data is transmitted to each Drone sta- 
tion in packets, with individual error 
checking. Typical system response time 
for program loading is two seconds. 

Cluster/One commands are quite 
similar to their counterpart cassette 
tape commands. Disk commands may be 
imbedded in user programs, permitting 
menu-driven program loading or chain- 
ing. 

Cluster/One comes with a full set of 
utility programs for system maintenance 
and backup, along with separate doc- 
umentation for the end users. Prices 
begin at $45 00 and vary with the parti- 
cular configuration and options selected. 
For further information, contact Nestar 
Systems Inc, 810 Garland Dr, Palo Alto 
CA 94303. 

Circle 573 on inquiry card. 



Where Do New Products Come From? 

The information printed in the 
new products pages of BYTE is 
obtained from "new product" or 
"press release" copy sent by the 
promoters of new products. If in 
our judgment the information 
might be of interest to the per- 
sonal computing experimenters 
and homebrewers who read 
BYTE, we print it in some form. 
We openly solicit releases and 
photos from manufacturers and 
suppliers to this marketplace. The 
information is printed more or 
less as a first in first out queue, 
subject to occasional priority 
modifications. While we would 
not knowingly print untrue or 
inaccurate data, or data from 
unreliable companies, our capa- 
city to evaluate the products 
and companies appearing in the 
"What's New?" feature is neces- 
sarily limited. We therefore can- 
not be responsible for product 
quality or company performance. 



Heat Scalable Cassette Holder 




This cassette holder, designated 
Pocketray, will hold a cassette securely 
with the title visible. Cassettes are fully 
protected on three sides. There are 12 
Pocketrays to a sheet which is perforated 
vertically and horizontally. These may 
be snapped apart into single units or in 
any multiple to fit the most creative con- 
figuration. Made of PVC, these cassette 
holders are easily heat sealed to any 
vinyl material, with a minimum of tool- 
ing. Samples, pricing, and literature are 
available from Charles Leonard Inc, 
79-11 Cooper Av, Clendale NY 11227. 
Circle 574 on inquiry card. 



216 September 1979 © BYTE Publications Inc 



FLOPPY DISK 
REPAIR 

• PerSci and Shugart 

• Quick turnaround 

• Factory trained on 
PerSci 

TKc:';;;; i; !lV>:;;;::::*T^ , T :^t> "^'W 

COMPUTER SERVICE CENTER 

7501 Sunset Blud 

Hollywood CA 90046 

213-851-2226 



Circle 68 on inquiry card. 



GET CONNECTED 



Connect your S-100 BUS or 
TRS-80 system to the telephone 
network and turn it into a terminal. 
The ^-Phone© is absolutely all 
you need — it's not just a modem, 
not just a controller. 

Just plug the /i-Phone© into your 
processor and plug it's cable into a 
standard modular telephone wall 
jack and you're connected. 

The fi-Phone© is BELL 103 com- 
patible and F.C.C. registered. 

Another Fine Idea From 

I.D.E.A. 

850 Lexington St. 

Waltham, MA 021 54 

617-893-1368 



Circle 178 on inquiry card. 



BASIC/FOUR COMPUTER 
MODEL 350 

Perfect for small to medium 
sized business applications. 
Model 350 CPU, 4.2 Mb 
Disc Drive, Video Display Ter- 
minal, 1 60 cps Printer, and 6 
Disc Cartridges. Under con- 
tinuous factory maintenance. 
Full system ready to go 
$11,000. 

Contact: 
Carl Egetter (714) 979-9013 
THERMAX SYSTEMS, INC. 

3185 "A" AIRWAY AVE 
COSTA MESA, CA 92626 



Come Help Us 
Celebrate The Child 

St. Jude Children's Research 
Hospital continues its search for 
life-saving knowledge about 
catastrophic childhood disease. 
And this search continues 
because people care. There's 
no charge to patients or their 
families, once admitted to its 
research studies by physician 
referral. The cost of drugs, 
equipment, and research 
programs is met primarily 
by public contributions. Help 
us celebrate the child by send- 
ing your fax-deductible check 
or request for further informa- 
tion to St. Jude Children's 
^ _ Research Hospital, 
k A™ 539 Lane Ave., 
ifej Memphis, TN 36105. 



Don't Forget! 

Our New 4K Byte Non-Volatile 
Memory Boards Won't Let You! 

• 30 days minimum guaranteed 
data retention 

• Ultra low power 450 NSEC 
static CMOS RAM IC's 

• On-board regulator, power 
monitor and battery 

• S-100 bus compatible 

Assembled and Tested 
$395.00 

Remember . . . 

to send for details! 



1395 Golf Street 
Dayton, Ohio 45432 



Circle 88 on inquiry card. 



TRS-80 USERS 

Three Diskless TRS-80 Programs 

- Telephone/Address/Mailing list pro- 
gram - sorts by name or zip code. 
Retrieves telephone § from name and 
visa versa. Access time is under 2 
seconds, over 100 listings, Level II 16K 

-$30.00 

- Checkbook program - hard electronic 
copy, easily accessable. 170 listings, 
Level II 16K -$30.00 

- Mandalas for the Cybernectic Age I & II 
-amazing graphic programs, better than 
TV - lasts hours without repeating or 
commercials. 2 sets of four interweaving 
designs, Level I or II 4K RAM 

- $30.00 
Introductory offer - All 3 for $75.00 
Loweco provides complete support 
Catalog $2.00 

LOWECO COMPUTOR 

1803 RODNEY 

LOS ANGELES CA 90027 

213-660-7530 

6% TAX IN CALIFORNIA 
Money Order, Cashier Check Speeds Delivery 



TRS-80, PET, 
APPLE, 

SORCERER 

Hardware/Software 
Systems 



Available now: 

■ HAM INTERFACE-including the 
most sophisticated RTTY systems 
money can buy. 

■ Baudot and ASCI I printer 
interfaces. 

M Electra Sketch' .ANIMATION 
GRAPHICS Compiler 

Write or call for free catalog 

>VWCROTRONICS,inc. 

P.O. Box 518 (a ) Keyes, CA 95328 
(209) 634-8888 / 667-2888 (R) (S) 

We are experiencing telephone difficulties, 
please keep trying. 



Circle 206 on inquiry card. 



EXCELLENT BUY: 
USED CENTRONIC PRINTERS 




Model 703 $1495. 

Model 588 S 895. 

COMPLETE 

TIME SHARING 

AND 

IN-HOUSE 

SYSTEMS AVAILABLE 

Texas Instrument 
3n Teletype 
m£ Xerox 
Intertec 
Altos 

Ohio Scientific 
Exidy 
Centronics 




Circle 74 on inquiry card. 



A Message 
to our Subscribers 

From time to time we make the BYTE 
subscriber list available to other com- 
panies who wish to send our subscribers 
promotional material. We take great care 
to screen these companies, choosing 
only those who are reputable, and whose 
products, services, or information we 
feel would be of interest to you. 

While we believe the distribution of this 
information is of benefit to our 
subscribers, we firmly respect the 
wishes of any subscriber who does not 
want to receive such promotional 
literature. Should you wish to restrict the 
use of your name, simply send your re- 
quest to 

BYTE Publications Inc 

Att: Circulation Department 

70 Main St 

Peterborough NH 03458 

Thank you. 



Circle 367 on inquiry card. 



Circle 207 on inquiry card. 



Wtisfs New? 



SYSTEMS and MEMORY 



New Word Processing System Also Supports Data Processing Applications 



A video based word processing sys- 
tem capable of handling data processing 
applications has been introduced by 



Vector Graphic Inc, 31364 Via Colinas, 
Westlake Village CA 91361. The new 
system, called Memorite 2, incorporates 




the firm's Z80 based MZ microcom- 
puter with 630 K bytes of disk capacity, 
their Mindless Terminal, and the Qume 
Sprint 5, 55 cps printer. For word 
processing applications, Memorite 2 with 
dual Micropolis floppy disk drives 
features advanced text preparation, edit, 
and delete capabilities. It offers auto- 
matic letter printing from memory with 
full formatting techniques such as under- 
lining, indentation, automatic margins 
and variable line and character spacing. 
The system also performs mass mailings, 
which allow letters to be merged with 
address lists. Its memory is resident on 
programmable read-only memory, so 
users need only type after a "power up 
and proceed" function. 

As a data processor, Memorite 2 is 
capable of performing standard account- 
ing tasks and custom applications in 
business BASIC for small firms or 
departments of large companies. Scien- 
tific calculations are also available for 
technical environments. 

The price for the Memorite 2 is 
$8,950. 

Circle 575 on inquiry card. 



CATCH THE 

S-100INC. 

BUS! 



Vector Graphic 16K 
Assembled Fast Memory 
Board 

Imsai "8080" Kit complete 
w/Front Panel 

Computime CT100 Clock, 
Calendar & Calculator Kit 

S-100's Three Ring Binder 

w/Ten Vinyl Jackets for 5 1 A 
Mini Floppies (Holds 
Twenty Diskettes Plus 
Directory Pocket) 




LIST 
PRICE 



OUR 

SPECIAL 

CASH 

PRICE 



485.00 350.00 



750.00 625.00 



199.00 170.00 



13.00 7.00 



Imsai 80/15 Kit w/8085 CPU 799.00 625.00 

We carry all major lines such as 

S.D. Systems. Cromemco. IMSAI, Vector Graphic. North Star. Sanyo. ECT. 

TEI. GorJIioul. Thinker Toys. Hazeltine. IMC 

For a special cash price telephone us. 

Subject to Available Quantities • Prices Quoted Include Cash Discounts 
Shipping & Insurance Extra. 



Bus. 
Address. 

Interface. 



.S-JQD,inc. 

7 White Place 
Clark, N.J. 07066 
201-382-1318 



Non-Volatile Memory Board 




The E4K EAROM Memory Board pro- 
vides a Multibus compatible nonvolatile 
memory of up to 4 K words by 8-bit 
capacity. The memory contents are elec- 
trically alterable under computer con- 
trol, permitting it to function as a pro- 
grammable memory but with the advan- 
tage of long term unpowered data reten- 
tion. Either word or block erasure is 
possible. Operating software listings are 
provided with the board. Typical appli- 
cations include remote data acquisition 
systems, numerical control systems, pro- 
cess controllers, storage of manually 
entered constants and telephone number 
storage. 

The prices for the E4K EAROM 
Memory Board start at $420. For further 
information, contact Schneider Instru- 
ment Co, 8115 Camargo Rd, Madeira OH 
45243. 

Circle 576 on inquiry card. 



218 September 1979 © BYTE Publications lnc 



Circle 316 on inquiry card. 



HE MM- 103 DA TA MODEM 

AND COMMUNICA TIONS ADAPTER 



FCC APPROVED 



S-100 bus compatible 



Both the modem and telephone system interface are 
FCC approved, accomplishing all the required protective 
functions with a miniaturized, proprietary protective 
coupler. 



WARRANTY 



One year limited warranty. Ten-day unconditional 
return privilege. Minimal cost, 24-hour exchange policy 
for units not in warranty. 



HIGH QUALITY 



-50 dBm sensitivity. Autoanswer. Auto originate. Auto 
dialer with computer-controlled dial rate. 61 to 300 baud 
(anywhere over the long-distance telephone network), 
rate selection under computer control. Flexible, soft- 
ware-controlled, maskable interrupt system. 



ASSEMBLED & TESTED 



Not a kit! (FCC registration prohibits kits) 



LOW PRICE-S359. 95 - Bfi/BSIR, 



plus shipping 
& handling 



Potomac Micro-Magic, Inc 



Write for brochure: 
First Lincolnia Bldg., Suite B1 
4810 Beauregard St. 
Alexandria, Va. 22312 




Call for further information: 

VOICE: (703) 750-3727 

MODEM: (703) 750-0930 (300 baud) 




DATA TERMINAL EQUIPMENT FROM MICROMAIL 

T.I. 810 printer $1,695.°° 




S0R0C IQ 120 



$795.°° 



• RS 232C, upper/lower case, full 
ASCII 

• Numeric keypad, protected fields 

• Cursor keys plus addressable cur- 
sor 

• Auxiliary extension port 




LA34 DECwriter IV 

M.199" 

Upper/lower case, 9x7 dot matrix 

10, 12, 13.2, 16.5 characters/inch 

2, 3, 4, 6, 8 or 12 lines/inch 

22"W x 7"H x 15Vi"D, 25 lbs. 

110 or 300 baud, RS 232C serial 

ASCII 

Friction feed, paper width to 15" 



S0R0CIQ 140 * 1,250.°° 

• RS 232C and 20mA current loop 

• Extensive editing features 

• 25th line terminal status display 

• 16 function keys (32 with shift) 




New 
from DIABLO 

DIABL0 1640 *2,690.°° 
Receive-only $ 2,331 . 00 

High-quality daisywheel printing at 
45 cps. 

DIABLO 1650 5 2,779.°° 
Receive-only * 2,419.°° 

Metal daisywheel printing at 40 cps. 



Includes upper/lower case 
150 characters per second 
RS 232C serial interface 
Adjustable forms tractor 




NEC Spinwriter 

Call or write for prices 



To Order: Send certified check (personal or company checks require 
two weeks to clear) including handling* and 6% sales tax if delivered 
within California. 

'Handling: Less than $2,000, add 2%; over $2,000, add 1%. Everything 
shipped freight collect in factory cartons with manufacturer's warranty. 



cKHCRQklfllL 



MICROMAIL • BOX 3297 • SANTA ANA, CA 92703 
(714) 731-4338 



Circle 223 on inquiry card. 



BYTE September 1979 219 



Circle 227 on inquiry card. 



Paul McCoy Enterprises, Inc. 

Software 



TM 



NARKLE™ 

The NAME, ADDRESS, REFERENCE, KEYWORD, LETTER, ENVELOPE SYSTEM. 

DATA FILE 

NARKLE ™ is an interactive, menu-operated system that allows the creation, 
maintenance, up-date, delete, etc, of a mailing information file. 

Using the 100 reference fields you can store data about each client and also 
use this data as a means of automatically building smaller more specific files. 
Also, you can list files, view individual records by name or record number, 
and so much more. 

LETTER 

Using the NARKLE data file and your text editor, NARKLE will create hand- 
crafted personalized letters completely automatically. It features automatic 
data file name insertions in the inside address, salutation, and the body of 
the letter; either first name or title last name. Up to 25 ^keywords" can be 
used, and so much more. 

NARKLE is the most polite data system on the market today, easily operated 
by secretarial personnel with a few hours' instruction. 
NARKLE is sold on diskettes and includes a 43-page operator's manual. 



Paul McCoy Enterprises, Inc.™ 

300 E. 30th Street, Austin, Texas 78705 
Phone: (512) 476-1700 

Hardware required for NARKLE and XTABFREQ: 8080 or Z-80 Based 
Microcomputer/ 48k of memory/CP/M or similar software/CBASIC, Disk 
drive(s) and interface, terminal and printer. 



XTABFREQ™ 

The CROSSTABULATION, FREQUENCY, STATISTICS, ENTRY SYSTEM. 

XTABFREQ is a completely interactive system which secretarial personnel 
should be able to operate with only a few hours of instruction. 

The crosstabulation routine can operate in two or more dimensions, 
generating cell count, cell row and column %, as well as cell % of total table. 
The routine delivers Chi-Square, Degrees of Freedom, Lambdas, Uncertainty 
Coefficients, Etas, Kendall's Tau B and Tau C, Gammas and Somer's D. The 
SPSS'" user will find XTABFREQ NOT TO BE A COMPROMISE but much more 
convenient and versitile. 

FREQUENCY 

Besides for Absolute Frequency the routine generates Adjusted, Relative and 
Cumulative Frequency. Also a code and symbol for Weighting can be used 
with the Raw Count. 

You also get the Mean, Mode, Kurtosis, Minimum, Maximum, Range, 
Standard Error, Standard Deviation, Skewness, Median, and Variance. 

REFENTRY 

Both the Crosstabulation and the Frequency Routine utilize the very powerful 
data entry and management routine, REFENTRY™. This routine lets you easily 
build, examine, store on diskettes, manipulate, and extract files for your 
XTABFREQ JOBS. XTABFREQ will also accept NARKLE™ File interactively. 

With XTABFREQ you can predict tomorrow without waiting for punchcards. 
XTABFREQ is sold on diskettes with a 37-page operator's manual. 

Send $175 for Narkle and $295 for XTABFREQ. Manuals are available at 
$10 each. Dealer inquiries welcome. 



SPSS™ is a copyright of McGraw-Hill, Inc. 




220 BYTE September 1979 



Circle 291 on inquiry card. 



Circle 79 on inquiry card. 



Circle 91 on inquiry card. 



PET WORD PROCESSOR 




This program permits composing and printing letters, 
flyers, advertisements, manuscripts, etc., using the 
COMMODORE PET and a printer. 
Script directives include line length, left margin, cen- 
tering, and skip. Edit commands allow the user to 
insert lines, delete lines, move lines and paragraphs, 
change strings, save onto cassette, load from cassette, 
move up, move down, print and type. 
The CmC Word Processor Program addresses an RS- 
232 printer through a CmC printer adapter. 
The CmC Word Processor program is available for 
$29.50. Add $1.00 for postage and handling per order. 

Order direct or contact your local computer store. 



CONNECTICUT microCOMPUTER 

150POCONO ROAD 

BROOKFIELD, CONNECTICUT 06804 

(203) 775-9659 

TLX: 7104560052 



NO FRILLS! NO GIMMICKS! JUST GREAT 

DISCOUNTS 

MAIL ORDER ONLY 



HAZELTINE 

1400 $679.00 

1500 995.00 

Mod 1 1495.00 

CENTRONICS 

779-1 954.00 

779-2 995.00 

700-2 . 1350.00 

761 KSR tractor 1595.00 

703 tractor 2195.00 

MicroPrinter 395.00 

NORTHSTAR 

Horizon I assembled. . 1629.00 

kit 1339.00 

Horizon II assembled . 1999.00 

kit 1599.00 

Disk System 589.00 

TELETYPE 

Mod 43 995.00 



DIGITAL SYSTEMS 

Computer $4345.00 

Double Density 
Dual Drive 2433.00 

IMSAI 

VDP 80/1000 $5895.00 

VDP44 4195.00 

16K Memory assem.. 399.00 
PCS 80/15 679.00 

15% oil on all other Imsai products 

DEC 

LA34 1149.00 

CROMEMCO 

System III $1000 ott . 4990.00 

10% off on all other 
Cromemco products 

TEXAS INSTRUMENTS 
810 Printer 1595.00 



Mosl items in stock for immediate delivery. Factory-fresh, sealed cartons. 

DATA DISCOUNT CENTER p.o.box-ioo 

135-53 Northern Blvd., Flushing, New York 11354, 212/465-6609 

N.Y.S. residents add appropriate Sales Tax. Shipping FOB N.Y. 
I BankAmericard, Master Charge add 3%. COD orders require 25% deposit 




CP/M 



® 



LOW-COST 

MICROCOMPUTER 

SOFTWARE 

CP/M® OPERATING SYSTEM: 

• Includes Editor, Assembler, Debugger and Utilities. 

• Standard version for 8080, Z80, or Intel MDS 
(other versions available.) 

• For IBM-compatible floppy discs. 

• $100-Diskette and Documentation. 

• $25-Documentation (Set of 6 manuals) only. 

MAC™ MACRO ASSEMBLER: 

• Compatible with new Intel macro standard. 

• Complete guide to macro applications. 

• $90-Diskette and Manual. 
SID™ SYMBOLIC DEBUGGER: 

• Symbolic memory reference. 

• Built-in assembler/disassembler. 

• S75-Diskette and Manual. 
TEX™ TEXT FORMATTER: 

• Powerful text formatting capabilities. 

• Text prepared using CP/M Editor. 

• $75-Diskette and Manual. 
DESPOOL™: 

• Background print utility. 

• Use with CP/M (version 1.4) 

• $50. Diskette and Manual. 

1 DIGJTflL RESEARCH 

P.O. Box 579 • Pacific Grove, California 93950 
(408) 649-3896 



® 



UNCOMPROMISED 

QUALITY AND 

PERFORMANCE IN A 

JOYSTICK FOR YOUR 

APPLE II* 

Available now from 
your local dealer 

$65 

I or by mail from 



Whether for technical/graphics or a more realistic 
game of Star Wars, you' 11 love this precision gimballed 
joystick with self-centering action and unique capacitive 
switch that activates with only a touch of the control shaft. 
Front panel accessible X and Y axis trimmers and input 
pushbutton are featured on the PAIA/ APPLE n Joystick. 
Plug compatible with the APPLE II game controller. 

Distributed by: High Technology, Inc. , Oklahoma City 
- Dealer Inquiries Invited - 



Send the PAIA/APPLE/n Joystick Controller □ $65. 00 plus 

$1. 50 postage enclosed. □ Charge VISA MC 

Card No. Expiration Date: 



address, 
city 



state 



zip 



ELECTRONICS DEPT. 9-8.1020W. WIISHIRE BLVD.. OKLAHOMA CITY, OK 73116 



Circle 95 on inquiry card. 



Circle 297 on inquiry card. 



BYTE September 1979 221 



Circle 93 on inquiry card. 



Circle 211 on inquiry card. 



25 START-AT-HOME 
COMPUTER BUSINESSES 

In "Low Capital, Startup 
Computer Businesses" 

CONSULTING • PROGRAMMING • MICRO COMPUTER 
OPPORTUNITIES • SOFTWARE PACKAGES • FREELANCE 
WRITING • SEMINARS • TAPE/DISC CLEANING • FIELD 
SERVICE • SYSTEMS HOUSES • LEASING • SUPPLIES • 
PUBLISHING • HARDWARE DISTRIBUTORS • SALES 
AGENCIES • USED COMPUTERS • FINDER'S FEES • 
SCRAP COMPONENTS • AND MORE . 

Plus — ideas on moonlighting, going 
full-time, image building, revenue 
building, bidding, contracts, marketing, 
professionalism, and more. No career 
tool like it. Order now — if not completely 
satisfied, return within 30 days for full 
immediate refund. 

• 8% x 11 ringbound • 156 pp. • $20.00 
Phone Orders 901-761-9090 



! 







DATASEARCH 

incorporated 
4954 William Arnold Road, Dept. B, Memphis, TN 38117 
Rush my copy of "Low Capital Startup Computer Businesses" at $20. 



NAME/COMPANY 
ADDRESS 



CITY/STATE/ZIP 



□ Check Enclosed 



□ VISA □ Master Charge 
Exp. Date 



KEYED FILE MANAGEMENT 



Put data at your fingertips. . .easily accessed, displayed and 
updated by key. Designed to meet all of your data management 
needs, MAGSAM'" allows you to quickly implement sophisticated 
keyed file structures through simple CBASIC statements. 
Standard MAGSAM'" features include record retrieval with random 
by key. sequential by key. and generic ("wild card") search, and 
complete compatibility with all CBASIC file facilities. Each 
MAGSAM'" Package includes the MAGSAM'" file manager. 
MAGSAMX'" tutorial program, MAGSAMD'" file dump utility. User 
Guide, Reference Card, and one year update service. 
Select the version of MAGSAM'" that meets your requirements. All 
versions of MAGSAM'" are completely upward compatible and 
may be upgraded at any time for the price difference. 

• MAGSAM III™ — Most advanced version. Multiple Key support 
(any number of keys), and Record and Key Deletion with automatic 
reclamation of disk space $145t 

• MAGSAM II'" — Single Key support with full Delete 
capability S99t 

• MAGSAM I'" — Entry level version. Single Key support without 
Delete capability S75t 

• User Guide only - comprehensive tutorial and reference 

manual $15 

Available for 8" soft sector. Micropolis, and TRS-80 disk formats. 
Requires CP/M - or derivative and CBASIC. Distributed as CBASIC 
subroutines in source form. 

Visa and Masterchagre welcome. Dealer and OEM inquiries 
invited 



RflMS) 



MICRO APPLICATIONS GROUP 

7300CALDUS AVENUE 
VAN NUYS. CA 91406 



' Trademark of Digital Research t Single site license 



SOFTWARE TOOLS 

■ C compilers and cross-compilers for 
PDP-11 's, LSI-11's, 8080's and Z/80's, with 
complete runtime library. The full lan- 
guage is supported with efficient code 
generation. 

■ Interface libraries giving access to all 
system directives for UNIXf RT-11, 
RSX-11M, RSTS/E, IAS, CP/M, CDOS and 
ISIS-II. 

■ A-Natural narrative assembler for 8080's 
and Z/80's with librarian and linking loader. 

■ Over 75 installations in less than six 
months. 

^UNIX is a trademark of Bell Laboratories. 

Continuing maintenance and training available. An 
affordable alternative to Assembler, Fortran or Pascal, 
for as little as $500 per compiler binary license. 
Catalogue and references available upon request. 
Write to ^ 1x1 

whitesmiths, Ltd. 

127 East 59th Street -NewYork NY10022- 212 799-1200 



WELL, 

BYTE MA BELL! 




TRS-80® 

Software-Level I & II, 
4k & 16k 



Have your TRS-80® computer dial the 
telephone ■ Dial 20 phone numbers, accessed 
by a single letter code ■ Operates with dial & 
pushbutton phones ■ Requires a simple 
interface using $4 worth of parts from Radio 
Shack" No internal connections are made to 
the TRS-80® ■ The program is supplied on 
cassette tape, with complete instructions ■ 
(Specify Level I or II with order) 

TRS-80" is a registered trademark of 
Tandy Corporation 



Write to : Software Exchange 
2681 Peterboro 
W. Bloomfield, Mi. 48033 , 




222 BYTE September 1979 



Circle 388 on inquiry card. 



Circle 332 on inquiry card. 



Creative Software Introduces: Programs & Products for the TRS-80 (16K level II) 



NEW! A supm JOYSTICK interface Un \U TRS-80! 

Three sockets allow you to use one I am liild" ur Iwo Atari*'" joysticks 
with no modilu alions to the I'RS-80 Joystick interlace with Iwo 




Jos/slicks lhain luld'" or Ai 



$65.00 
$12.50 



Household Finance I & II 



$15.00 



P. ut 1: Inputs data on each household expenditure: lisis. .ultls. updates, 
changes or deletes previously input items. Wines data In cassette tape. 
Part II: Reads data tape. Provides monthly and yearly summaries ol 

liii.im i.il data, simile < ategury summaries, and graphs .i upending ptolile 



ALSO: New Programs for the PET: 

PET Word Processor $75.00 

Complete word processing capabilities including uppet lowei case, 

string search, siring change .aid many other lealures lound on cum 
menial word processors. Package includes both text editoi and 
Formatter and requires 16K or H2K PET. 

PET Space War II $10.00 

Fantastic real time action! You .ire in complete control ol the Entet 
prise as you lend off aliens lo search the universe loi colonizublc 
planets. Requires the Creative Software single joystick lot the PET. 



Household Utility 1 $12.00 

(Ini'ludfb CiliMulai, Loans and Buy or Rem Programs) 



Household Utility 2 



$12.00 



Atnoi li/alion and C 



Many olhei Creative Software products .ire available lor the 
PET and TRS-80. II yout local denlei doesn't (any Creative 
Software products or program inlormation, write directly lo the 
address below. When placing an order please note: 
Specilv computet & progtarn(s). Add $1.50 shipping lor each 
program ordered, $2.50 lor joystick interlace. California residents 
add 6".. sales lax. VISA MASTKKCI 'AHGH accepted. Include 





PET Road Race 






. $10.00 


ureauve auuware 






Another great machine 
different tracks as you 


anguuge program gn 
brattle with your opp 


/es you a i 
menl to 1 


h<iu e nt ilucc 
nish the uk <■ 


P.O. BOX 4030, MOUNTAIN VIEW, CA 94040 






Includes oil slicks, auloi 


natic lap counters, a 


id an elap 


*c(l Mine i lot k 








showing tune to tenths 


ol seconds 










""""""" 



LET CR'liDS GET YOU THROUGH THE TAX SEASON 

— Standard and Master Tax Programs designed to prepare even the most complex returns. 

— General Ledger and Payroll, working in conjunction with the tax programs to further simplify tax preparation. 

— Tax Pacs used by individuals for at-home preparation. 

— NEW for this year — Corporation Tax Programs. 

CPAids 

• Microcomputer software developed by CPA's 

• Used Nationally the past two years 

• Available on North Star Basic and CP/M 

For more details write: 

Computer Tax Service • 1640 Franklin Ave. • Kent, Ohio 44240 
or contact the dealer nearest you: 



Alaska 

UBIQ 

500 L St. 

Anchorage, Alaska 99501 

California 

Coast Computer Center 
1685 Tustin Ave. #9 
Cost Mesa, Ca 92627 
Computerland 
6840 La Cienga Blvd. 
Inglewood, Ca. 90302 
Pro Data Group 
14522 Acacia Dr. 
Tustin, Ca. 92680 

Delaware 

Computer Ease, Inc. 
403 Milltown Rd. 
Wilmington, De. 19808 

Florida 

Computers For You, Inc. 
3608 W. Broward Blvd. 
Ft. Lauderdale, Fla. 33312 



International Computer 

Systems 
2210 Ponce-de-Leon Blvd. 
Coral Gables, Fla. 33134 

MISA 

478 NE 125th St. 

N. Miami, Fla. 33161 

P & L Computers 

2550 Palm Beach Lakes Blvd. 

Suite 208 

West Palm Beach, Fla. 33409 



Indiana 

Computer Center of 

South Bend 
19819 Orchard St. 
South Bend, In. 46637 



Iowa 

Central Computer 
1107 Airport Rd. 
Ames, Iowa 50010 



Louisiana 

Micro Business Systems 
3823 Gilbert 
Shreveport, La. 71104 

Maryland 

The Computer Workshop, Inc. 
1776 Plaza 
1776 East Jefferson 
Rockville, MD. 20852 

Michigan 

United Microsystems Corp. 
2601 South State St. 
Ann Arbor, Ml. 48104 

Minnesota 

The Computer Room, Inc. 
3928 Beau D'Rue Dr. 
Eagan, Mn. 55122 

New Jersey 

Computerland of Morristown 
2 Dehart St. 
Morristown, NJ 07960 



Tax Ease 
226 Avon Rd. 
Cherry Hill, NJ 08034 

New Mexico 

Microsys Inc. 
7800 Phoenix NE 
Albuquerque, NM 87110 

New York 

The Computer Corner 
200 Hamilton Ave. 
White Plains, NY 10601 
Micro Innovations 
420 Lexington Ave. 
NY, NY 10016 

North Carolina 

Byte Shop of Charlotte 
6341 Albemarle Rd. 
Charlotte, NC 28212 
Coastal Computer Co. 
P.O. Box 333 
Jacksonville, NC 28540 



Computerland of Charlotte 
3915 E. Independence Blvd. 
Charlotte, NC 28205 

Ohio 

Bethel Computers 
1700 E. Main St. 
Kent, Ohio 44240 
Computer Tax Service 
1640 Franklin Ave. 
Kent, Ohio 44240 

Texas 

Interactive Computers 
7620 Dashwood 
Houston, Tx. 77036 

Virgina 

Command Systems, Inc. 
727 23rd St. S. 
Arlington, Va. 22202 

Washington 

Magnolia Microsystems 
2812 Thorndyke Ave. West 
Seattle. WA 98199 



Circle 72 on inquiry card. 



BYTE September 1979 223 



Circle 330 on inquiry card. 



Circle 85 on inquiry card. 



RAM CHIPS 



4044 



TYPE 



4Kby1 — 18-pin — 5V, 5% supply 

These are the same factory prime chips used in our 
premium quality RAM boards. May be 4044, 4041, 
5257, 6641, or 9044, depending on manufacturer. All 
have 4044 pinout and timing specs. All guaranteed 30 
days. 



■doooiioimoeoinnioiiiiooo>iioiioo80»oo»iiiiotmooeaoooao8a80oooooo800Ciie88W8»MlHH»»»»8 »m 



1-31 chips 
32-63 
64-99 
100-499 



250 nsec. 

$7.50 
6.50 
5.75 
5.50 



450 nsec. 

$6.50 
5.50 
4.75 
4.50 



Circle Inquiry number for free newsletter. 



h 



Seattle Computer Products, Inc. 

1114 Industry Drive, Seattle, WA. 98188 
(206) 575-1830 



TRS-80 ... all business! ! 

...with CP/M, CBASIC2, 
& applications software. 

CP/M Operating System (w/Editor, Assembler, 

Debugger, Utilities & 6 manual set) $150 

CBASIC2 Compiler (w/manual) $ 95 

DESP00L Print Spooler (w/manual) $ 75 

*Osborne & Assoc. PAYROLL W/C0ST 

ACCTNG $250 

*Osborne & Assoc. ACCTS. RECEIVABLE & 

ACCTS. PAYABLE $250 

*0sborne& Assoc. GENERAL LEDGER $250 

*=CBASIC2 source programs; add $15 (each) for 
applicable O & A book. 

APH - Self-administered Automated Patient 

History $175 

| DOWNLOAD -TR-80 (or other) 

CP/M to CP/M $95 

data/program (source or object) transfer over 
RS232 link 

Send 30ri SASE for add'l. Software avail, (including 
CP/M Users Group software) and FREE "CP/M Primer." 

CA residents add 6% tax. Visa, M/C,M/0,Check OK. 



(714)848-1922 




aOdt NEWMAN AVENUE 






HUNTINGTON BEACH. CALIFORNIA 92647 



ffainrcinroT^ 



North Star* and 
PASCAL Users: 

JltUifce's 

announces 

Hard disk and 8" drive interfaces to North 
Star DOS and BASIC and PASCAL 



TIMESHARING 

for the Horizon — 

Interrupt-driven, bank switching 
timesharing software; supports 
North Star DOS and BASIC and 
PASCAL. 



A complete selection of business applica- 
tion software is available for North Star* 
systems. 

Write or call for descriptive literature. 

Micro Mike's, Incorporated 

905 South Buchanan * Amarillo, Texas 79101 * USA 
(806) 372-3633 



SORCERER* 
SOFTWARE! 



FOUR PROGRAMS ON CASSETTES 

FASTGAMMON™ by Bob Christiansen. Thousands of people are already playing FAST- 
GAMMON on TRS-80 and Apple. Now it is ready for SORCERER, with the sharpest graphics 
ever! Backgammon players love this machine language program that provides a skillful 
opponent. Eight-page instruction manual includes rules of backgammon. $19.95 

PLOT by Vic Tolomei. Now Apple owners will be envious of how easy you can get good 
graphics on your SORCERER. PLOT includes both a super high resolution mode and a quick 
low resolution mode. Both are accessible from your BASIC programs using simple com- 
mands. Hi-res & lo-res examples included on tape. 514.95 

Z-80 DISASSEMBLER by Vic Tolomei. Decode machine language programs, including 
SORCERER'S monitor and ROM-PACs, with this Z-80 Disassembler written in BASIC. In- 
struction mode prints out machine code and Zilog mnemonics in standard format. Or use 
the ASCII mode which converts machine code to ASCII. $14.95 

MAGICMAZE™ by Vic Tolomei. A challenging maze game. Ten levels of play. Holding your 
lantern, you wander through a maze trying to stay on the right path and avoid pitfalls. 
Automatic scoring tells you how good a pathfinder you are. $1 1.95 



SOFTWARE INTERNALS MANUAL FOR THE SORCERER by Vic Tolomei. A musl for 
anyone writing software for the SORCERER. Seven chapters: Intro to Machine 
Language, Devices & Ports, The Monitor, Cassette Interface, BASIC structure, 
Video & Graphics, The Keyboard. Indexed. Includes diagrams and software rou- 
tines. 64 pages. 514.95 




QUTlLITy SOFTWARE 

6660 Reseda Blvd., Suite 103. Reseda, CA. 91335 
Telephone 24 hours, seven days a week: (213) 344-6599 

WHERE TO GET IT: Ask your nearest Sorcerer dealer to see Quality Software's Sorcerer 
programs. Or, if you prefer, you may order directly from us. MasterCharge and Visa card- 
holders may telephone their orders and we will deductSI from orders over S19 to compensate 
for phone charges. Or mail your order to the address above. California residents add 6% sales 
tax. Orders outside North America add $5 for registered airmail, pay in U.S. currency. 
" The name "SORCERER" has been trademarked by Exidy, Inc. 



224 BYTE September 1979 



Circle 204 on inquiry card. 



Circle 321 on inquiry card. 



10-DAY FREE TRIAL 



Send for our 
FREE Catalog 




Keyboard C 
Keyboard C 
Keyboard B 
Keyboard N 
Keyboard C 
Keyboard B 
Keyboard N 



4K 
8K 

16K 
16K 
32K 
32K 

32K 

C — calculator keyboard (only version with tape deck) 

B — Large Keyboard (graphics not on keys) 

N — large keyboard with graphics symbols 

Used 8K PET with 90-day warranty $650 



WE BUY USED PET APPLE and TRS-80 COMPUTERS 

$100 FREE ACCESSORIES 

WITH 16K0r 32KPET 



Terminal Package with 8K 

PET ACCESSOR 

Commodore Dual Floppy Disk Drive 
NEW! T/C 2001 Terminal Package for 

Second Cassette — from Commodore 

Commodore PET Service Kit 

Beeper • Tells when tape is loaded 

Petunia - Play music from PET 

$ 595 Video Buffer - Attach another CRT 
$ 795 Combo - Petunia and Video Buffer 

$995 Betsi 4-slot S-100 Motherboard 

$ 995 S-100 PET Interface was $289.00 SALE 
$1195 New Serial Printer Interlace lor PET . . 
$1195 Integral Data Printer w new interface 
$1195 pet - Compatible Seleclric in Desk 
TTY KSR-33 Screen Printer lor PET 
Ca 



u 




Hazeltine 1400 

LIST SALE 



$1295.00 

the PET $69.00 

$95.00 

$30.00 

$24.95 

$29.95 

$29.95 

$49.95 

$119.00 

$99.00 

$79.95 

$878.95 

$895.00 

$395.00 



I lor Availability 

Originate Answerback Modem lor PET 
Bi-directional RS-232 Interfac 



Q3X3 



CBS31 



$320.00 
$280.00 




apple II 

200 FR€€ RCC€SSOfll€S 

The new Apple II with Applesoft BASIC built-in! Elimi- 
nates the need lor a $200 Firmware Card and includes 
new Autostart ROM for easy operation. This combined 
with the FREE accessories from NCE could save you up 
to S400 on a 48K Apple II system! 

16K Apple II Plus — $11 95 (take $100 in free accessories) 
32K Apple II Plus — $1345 (take $150 in free accessories) 
48K Apple II Plus — $1 495 (lake $200 in free accessories) 



Apple II Accessories 

Centronics Printer Interface 

Disk and Controller 

Second Disk Drive 

Parallel Printer Card 

Communications Card 

Hi-Speed Serial Card 

Firmware Card 
Hobby Proto Card 



»22S 

Call lor Availability. $595 
$495 
$180 
$225 
$195 
$200 
$24 




OF THE 
MONTH 



Call for 
Availability 



Microverter RF Mod $35 

Sanyo M2544 Recorder $55 



APPLE II PRINTER PACKAGE $995 

For this low, low price, we choose a Centronics Impact 
Printer and match it up with an interlace and cable for 
your Apple II. You save hundreds of dollars. Limited 
quantities available. 



*5Q 



# 



New 300 baud 
Originate Answer 
Acoustic Coupler. 
Looks good, works 
great and sale 
priced at 



^$189 




CAT 
COUPLER 



■ Desktop Selectrle-Based - 
Terminal $319! 

Super bargain while they last: A desktop terminal 
based on an IBM Selectric typewriter for only $319 
including documentation. These terminals were 
originally designed for use with timesharing sys- 
tems where top-quality printing was required. The 
IBM keyboard and printer are separated by a three 
foot cable and each has its own enclosure (great for 
custom installations!. Serial RS-232 interface uses 
PTTC instead of ASCII codes so you will need to write a 
conversion program (we have ho ASCII interface for 
this model). 14.8 cps, 134.5 baud 13" line length, pica. 
Sold in AS-IS condition, our warranty is limited to 
replacement of missing parts (we check all motors). 



IN STOCK NOW 

EVERY ITEM IN THIS ADVERTISEMENT IS IN STOCK 
AND READY TO SHIP, EXCEPT WHERE NOTED. 



SAVE UP TO 43% Whlle ,he * last 

CENTRONICS PRINTERS 

Refurbished excellent working condition. 
10 day return privilege of course. 

90-DAY 

SPEED WIDTH PRINT WORKING WARRANTY 
MODEL (Ipm) (col's) MATRIX PRICE PRICE 



SUPER SALE PRICE 
TOO LOW TO ADVERTISE 

Immediate Delivery — 2-Year Factory Warranty 
You may have seen the Hazeltine advertised at $850. You 
may have seen it sale prices at $749 or even $699 but our 
new price is so low that we can t even advertise it. Call us 
for a quote Hurry, we have a limited quantity at this price 
The 8048-based Hazeltine 1400 has a 12 screen. 24x80 
display. TTY-style keyboard, addressable cursor and 
RS-232 I O from 110 to 9600 baud 

Hazeltine 1410 — $835 

Adds a 12-key numeric keypad to the 1400 tor financial or 

mathematical applications. 2-year warranty. 

Hazeltine 1500 — $1069 

Full-capability terminal complete with 12" screen. 24 x 

80 display, upper lower case, dual intensity. 

Hazeltine 1510 — $1195 

Additional memory is added to provide buffered data 

entry operations with editing capabilities 

Hazeltine 1520 — $1499 

Buffered like the 1510 but a microprocessor has been 

added to offer independent printer control. 



CRT TERMINAL PRINTER PACKAGE 

Hazeltine 1520 and a Centronics 761-5 together for only 
$2,295. The perfect work station for use with a buffered 
communications system. Terminal operations and print- 
ing may operate simultaneously. • Refurbished 



4> 



700 13-90 132 5x7 


660 


1 075 


Character Elonqation 






701 25-120 132 5x7 


695 


1 175 


Char Elong Bidirectional 






761 60 132 7x7 


695 


1 025 


Teleonnter Bidirectional 






"Model 761 includes Keyboard 







NCE/CompuMart 



SELLING COMPUTERS BY MAIL 
SINCE 1971 

1250 North Main Street, Department BY99 
P.O. Box 8610 Ann Arbor, Michigan 48107 

(313) 994-3200 



' Member: 
Computer Dealers 
Association 



, Inc. 



SANYO MONITOR 

9-inch 15-Inch 

-$£40. $169 -$400. $279 



SANYO 
MONITOR 

when you buy the 

SORCERER 

$995 

Z-80 Processor • Full-size keyboard • User definable 
characters • Up to 32K on-board RAM • Interchangeable 
ROM PACs- 30x64 display -Resident 4k monitor ROM- 
Dual Cassette I/O • Serial and Parallel I/O ■ Complete 
operator's manual 

Simply add a monitor and tape decks to complete the 
system. Can be used as a terminal Microsoft BASIC 
ROM PAC is standard. NEW! Exidy Word Processing 
ROM PAC now available which handles tabs, search, 
replace, etc., many different printers and can be used 
with cassette or disk. The most flexible W, P system we've 
ever seen. 

Sorcerer 8K $995 

Sorcerer 16K $1150 

Sorcerer 32K $1395 

Word Processing ROM PAC Call lor Availability $99 




IMPORTANT ORDERING INFORMATION 

All orders must include 4% shipping and handling. Michigan residents 
must also add 4% for state sales tax. All foreign orders (except Canada) 
need an additional 10% for shipping and handling. We cannot process 
your order without these. 



Phones open from 9:00 a.m. to 7:00 p.m. EST Monday-Friday, 10:00 a.m. to 
5:00 p.m. Saturdays • P.O.'s accepted from D & B rated companies — ship- 
ment contingent upon receipt of signed purchase order • All prices 
subject to change without notice • Most items in stock for immediate 
shipment — call for delivery quotation • Sorry, no C.O.D.'s • 
In the Ann Arbor area? Retail store open 1 1:00 a.m. to 7:00 p.m. Tuesday- 
Friday, 10:00 a.m.to 5:00 p.m. Saturdays (Closed Sunday and Monday) 



Circle 283 on inquiry card. 



BYTE September 1979 










YOUR #1 SOURCE FOR 



California Computer Systems 

Available at HOBBY WORLD 



Model 2500A 
S-lOO 

Wire Wrap 
Board 

• 5-100 BUS compatible 

• Double sided PC board 

• Plated thru holes 

• Perimeter ground 

• All S-100 BUS signals labeled 
and numbered 

• Accommodates standard size 
IC sockets 

• 4 to-220 regulator positions 
available 

• Allows either positive or neg- 
ative regulators 

• Dense hole configuration 
. Cat No. 1600 $ 27.00 



Model 2501A 
S-lOO 

Solder Board 

• 5-100 BUS compatible 

■ Double sided PC board 

■ Plated thru holes 

• Perimeter ground 

• All $-100 BUS signals labeled 
and numbered 

• Accommodates standard size 
IC sockets 

• 4 to-220 regulator positions 
available 

• Allows either positive or neg- 
ative regulators 

• Dense hole configuration 
.Cat No. 1604 $ 27.00 



[Model2501AS-100l 

Mother Board 

• 12 slot capability 

• All 12 S-100 bus connectors in- 
cluded 

• Low inductance inner-conned 
to reduce signal noise and 
crosstalk 

• Active termination of all bus 
lines to further reduce signal 
noise and line reflections 

• Distributed bypassing of all 
power lines 

• Solder mask both sides of 
board 

• Silkscreen of reference desig- 
nations 

• Simple strong hoard mounting 

• Criss-cross BUS lines both 
sides of board 

• All holes plated thru 

• Solder plated circuit area 
Cat No. 1616 Kit $ 90.00 

l Cat No. 1615 A&T $105.00 . 



Model 2520A 
S-lOO 

Extender/ 
Terminator 

• Active and/or dynamic term- 
ination 

• All power lines fused (or pro- 
tection 

• All S-100 lines labeled and 
numbered 

• Can be used as an extender 
and/or terminator 

• Solder mask both sides of 
board 

Silkscreened reference desig- 
nations 

• Gold plated fingers 

.Cat No. 2520 Kit S 37.95 . 



Model 7811 A 

Apple II 
Arithmetic 
Processor 

| • Based on AMD AM9511 de- 
vice 
1 Fixed point 16 and 32 bit op- 
eration 

I • Floatingpoint 32 bit operation 

• Binary data formats 

• Add, subtract, multiply, and 
divide 

I • Trigonometric and inverse tri- 
gonometric functions 
I * Square roots, logarithms, ex- 
ponentiation 
| * Float to fixed and fixed to float 
conversions 
1 Slack oriented operand stor- 
age 
■ Programmed I/O data transfer 

• End signal selectable interrupt 

• Supports interrupt daisy chain 

• Allows DMA daisy chain 

• Power down ROM 

| • 256 bytes firmware (ROM) or 
software (RAM) space avail- 
able 

I Cat No. 1635 $375,00 



Model 7114A 
Apple II 

Prom Module 

The 7114A PROM MODULE per- 
mits the addition or replacement 
of the Apple II firmware without 
the physical removal of the Apple 
II ROMS. This allows soft- 
ware/firmware replacement, 
change, and/or patch to be made 
on a ROM or BYTE BASIS. An 
on-board enable/disable toggle 
switch rs also available. 

• BYTE oriented program over- 
lay 

" Selectable prom overlay 

• Power down of PROMS 

• 14K PROM space available 

I • Uses +5 volt 2716 type proms 

1 Allows use of DMA/interrupt 

daisy chains 

I Cat No. 1631 A&T $ 72.00 

L Cat No. 1630 Kit $ 62.00 



Model 2016B 
s-ioo 

16K Static 
Memory 

• Fully static operation 

• Uses 2114 type static rams 

• +8 VDC input at less than 2 
amps 

• Bank select available by bank 
port and bank byte 

• Phantom line capability 

' Addressable in 4K blocks in 4K 
increments 

• 4K blocks can be located any- 
where within 64K bank 

• May be used as a 4K, 8K, 12K 
or 16K memory board 

• Led indicators for board/bank 
active indication 

, • Solder mask on both sides of 
board 
' Silk screen with part and refer- 
ence designation 
1 Available fully assembled and 
tested, as a kit, or as a bare 
board 
| Cat N0.I6OIA Kit 450ns 5285.00 
Cat N0.I6OIB Kit 200ns $340.00 
1 Cat No. 1602 A A&T 450ns $330.00 
LC.1I No.16A2B A&T 200ns $385.00 , 



Model 7470A 
Apple II 

3 3 A Digit BCD 
A/D 
Converter 

The 7470 allows conversion of a 
DC voltage to a BCD number for 
computer monitoring and analy- 
sis. Typical inputs would be DC 
inputs from temperature or pres- 
sure transducers. 
" Selectable interrupt on end of 
conversion 

• 20QUS per conversion 

• -4 to +4 VDC full scale 

• Plus or minus .05% nanlinear- 

ttv 

• Plus or minus 1 count quanti- 
zation 

• Correctible offset error 

• Temperature coefficient ad- 
justment 

• Calibration adjustment 

• Input offset adjustment 

• Floating inputs 

• Overange and sign indicators 

• Input filter 

• Power down ROM 

■ Supports interrupt daisy chain 

• Allows DMA daisy chain 

• 256 byte firmware (ROM) or 
software (RAM) space avail- 
able 

Cat No. 1621 Kit $115.00 
LCat No. 1622 A&T $135.00. 



Model 2200A 

Mainframe 

S-100 compatible 
Industrial/commercial quality 
construction 

• Flip-top cover 

• Excellent cooling capability 

• 12 slot capability (uses model 
2301 A) 

• Input 105. 115, or 12S VAC 

• Output +8 VDC, 20A + -16 
VDC 4A 

• Active termination of all bus 
lines 

Fan and circuit breaker includ- 
ed 

• Rugged construction 

• All parts available separately 
Cat No. 1612 Kit $330.00 

L Cat No. 1614 A&T $375.00 . 



Model 7440A 
Apple II 

Programmable! 
Timer Module 

■ Flexible external interface 
patch area for custom inter- 
face applications 

• Selectable prescaler on timer 
3 capable of 4mhz input 

• Programmable interrupts 

• Readable down counter indic- 
ates counts to go to time-out 

• Selectable gating for frequen- 
cy or pulse width comparison 

• Three asynchronous external 
clock and gale/trigger inputs 
internally synchronized 

• Three maskable outputs to 
patch area 

• Power down ROM 

• Supports interrupt daisy chain 

• Allows DMA daisy chain 

• 256 byte firmware (ROM) or 
software (RAM) space . 
able 

Cat No. 1617 Kit $135.00 

kCal No. 1618 A&T $145.00 A 



Apple II 
Model 771 2A 

Synchronous 

Serial 

Interface 

• Conforms to RS-232C [config- I 
uration A thru E) 

• Supports half or full duplex | 
operation 

• DTE type configuration 

• Failsafe RS-232C operation 

• 14 STD CLK rates 50-19.2K 
BAUD plus EXT CLK 

• BAUD rates dip switch select- 
able 

• All BAUD rates crystal con- 
trolled 

" Programmable interrupts from 
transmitter, receive;, and error 
detection logic 

• Character SYNC by one or two 
SYNC codes 

I • Programmable SYNC code re- 
gister 

I * Standard synchronous signal- 
ing rate per RS-269JANSI X3.1- 
1976 

Peripheral/modem control 
functions 

I • Three bytes of fifo buffering 
on both transmit and receive 
date 
7,8, or 9 hit transmission 

I * Optional odd, even, or no par- 
ity bit 

I • Parity, overrun, and overflow 
status checks 

I " Power down prom 

I • 256 bytes firmware (ROM) or 
software (RAM) space avail- 
able ' 

I • Supports interrupt daisy chain 

• Allows DMA daisy chain 
Leaf No. 1627 Kit $ 90.00 1 



Apple II 
Model 7710A 

Asynchronous 

Serial 

Interface 

• Parity, overrun, and framing I 
error check 

• Optional divide by 16 clock | 
mode 

• False start bit detection 

• Software programmable inter- | 
rupts 

• Data double buffered 

• One or two stop bit operation | 

• Power down PROM 

• 256 bytes firmware (ROM) or I 
software (RAM) space avail- 
able 

• Supports interrupt daisy chain 

• Allows DMA daisy chain 

• 134.5 BAUD available for sol | 
eclric interface 

• Conforms to RS-232C (config- 
uration A thru E) 

• Supports half or full duplex 
operation 

• OCR type interface 

• Failsafe RS-232C operation 

• 14 STD CLK rates 50-19.2K 
BAUD plus EXT CLK 

• BAUD rates dip switch selec- 
table 

• All BAUD rates crystal con- 
trolled except EXT 

• 8 and 9 bit transmission 

• Optional even, odd, and no 
parity bit 

• Programmable control regis- 
ter 

Cat No. 1624 A&T $145.00 
LCat No. 1623 Kit $ 90.00 A 



Model 7720A 
Apple II 

Parallel 
Interface 

Two bi-directional 8 bit buses 
for interface to peripherals 

• Tow programmable control 
registers 

• Two programmable data dir- 
ection registers 

• Four individually controlled 
interrupt input lines; two use- 
able as peripheral control out- 
puts 

1 Handshake control logic for 

input and output peripheral 

operation 
1 High impedance 3 stale and 

direct transistor drive pheri- 

pheral lines 

• Programmable interrupts 

1 CMOS drive capability on side 

A peripheral lines 
> 2 TTL drive capability on all A 

and B side buffers 
I ■ Power down ROM 

Supports interrupt daisy chain 

• Allows DMA daisy chain 

[ • 256 bytes firmware (ROM) or 
software (RAM) space avail- 
able 
I Cat No. 1633 A&T $105.00 
I Cat No. 1632 Kit $ 62.00 



Model 7500A 
Apple II 

Wire Wrap 
Board 

I The 750OA is used for the 

I prototyping or building of uniquel 

circuits for the Apple II 

computer. 

• All bus signals labeled on I 
board 

• Perimeter ground 

• Size: 7 inch long x 2.75 inch I 
high 

■ All holes plated thru 

• Gold plated conector fingers I 
Cat No. 1606 $ 19.00 | 

Model 751 OA 
Apple II 

Solder Board 

The 7510A is the same as the 
7500A except it is designed for 
soldering of circuits- 
1 Cat No. 1607 $ 19.00 

Model 7590A 
Apple II 

Etch Board 

1 The 7590A is a (wo sided copper | 
board which allows the actual 
etching of circuits for use in the | 
Apple II computer. 

I Cat No. 1608 $ 19.00 

Model 7520A 

Apple II 
Extender 



Board 



The 7520A is a handy tool 
when debugging or testing 
modules in the Apple II. 
ifal No. 1611 Kit $ 21.00 J 



19511 BUSINESS CENTER DRIVE 



226 BYTE September 1979 



Circle 170 on inquiry card. 



A 




I 



COMPUTER ELECTRONICS 



CALL TOLL FREE: 

(800)-423-5387 

CA, HI, AK: 
(213) 886-9200 



SOFTWARE 
SOFTWARE 

Star Trek III 

The most advanced ver- 
sion we've seen! 
TRS-80 L2, 16K 
Cat No. 1041 $14.95 

Backgammon 

You play against the com- 
puter! With hints on 
strategy, etc. Extremely 
good! TRS-80 L2-16K 
Cat No. 1481 $10.95 

Sargon Chess 

Winner of all tournaments! 
6 levels of play, excellent 

fraphics. 
RS-80 L2, 16K 
Cat No. 1093 $19.95 
Apple II, 16K 
Cat No. 1317 $19.93 

Tarot 

Excellent graphics, frigh- 
teningly accurate! 
TRS-80 L1/L2 4K 
Cat No. 1042 $5.95 

Air Raid 

An arcade-type real time 

fame of target practice, 
xcellent Graphics 
TRS-80 L1/L2 4K 
Cat No. 1186 $14.95 

Microchess 

Graphic Chessboard with 
3 levels of play. 
TRS-80 L1/L2, 4K 
Cat No. 1182 $19.95 

Apple II 

Cat No. 1183 $19.95 



CASSETTES 
CASSETTES 

Fortran Plus 

By Microsoft! For TRS-80 
L2 with 32K 



single 



and 
disk. 
Cat No. 1341 $340 

Beat the House 

4 Casino games: Black- 
jack, roulette, craps, slot 
machine. Excellent simu- 
lation. 

TRS-80 L2, 16K 
Cat No. 1347 $14.95 

Apple II, 16K 

Cat No. 1349 $14.95 

Level III Basic 

Gives your TRS-80 the 

fiower of a full size sys- 
em. Disk commands, ad- 
vanced editing, etc. 
TRS-80 L2, 16K 
Cat No. 1332 $49 

Bridge Challenger 

You and dummy play 
against the computer in 
regular contract bridge. 
Either you or comp sets 

TRS-80 L2, 16K 
Cat No. 1195 $14.95 

Apple 1GK 

Cat No. 1196 $14.95 

Machine 
Language Monitor | 

Allows you to interact dir- 
ectly with the TRS-80 at 
machine language level. 
11pp manual. 
TRS-80 L1/L2 
Cat No. 1048 $23.95 



Daily Biorhythm Electric Pencil 



Plots a 31 day graph cen- 
tered on the day you 
compute. 
TRS-80 L1/2 
Cat No. 1051 $5.95 



The famous word proces- 
sor for the TRS-80 L1/L2 
16K 

Cat No. 1338 $95 
L2 diskette version 
Cat No. 1338D $145 



VERBATIM 
574 Diskettes I 
$27 box of lO 

4 boxes for $1 OO 

Cat No. Type Us* 

1147 Soft sector TRS-80, Apple 

1148 Hard, 10 hole North Star 

1149 Hard, 16 hole Micropolis 



8" Disks 

$37 box of lO 

3 boxes for $100 

• IBM compatible 

• Single density 

• Individually certified 

I Cat No. 1145 Type 32-1000 
Description 
32 sector holes, 1 -index hole 

ICat No. 1146 Type 34-1000 
I interchangeable with IBM32,| 
I 3740, 3770, 3790, etc. 



EDGE 

CONNECTORS 

• Cold plated 

Description 

S-100, Imsai type, Solder- 
tail 
Cat No. 1376 Price $4.00 | 

S-100, Imsai type, wire- 
wrap 
Cat No. 1428 Price $4.25 

S-100, Altair-type, solder- 
tail 
Cat No. 1388 Price $4.00 

86-pin Motorola type, 

wirewrap 

Cat No.1389 Price $2.50 , 



from Novation 

CAT Acoustic 

Modem 




• For TRS-80, Apple, etc. 



Lets your computer talk 
to other computers over 
standard telephone lines. 
Also communicates with 
any Bell 103 compatible 



$195 



modem. Designed specifi- 
cally (or small computers! 
Fully assembled and tes- 



ted. 

Cat No. 1480 



Anadex Alphanumeric Printer 

$925 • For TRS-80, Apple, etc. 



Features 80 columns, 84 
lines per minute, super 
high reliability, 9x7 
character font. Completely 
self contained, perfect for 
terminals or as a stand 
alone printer. Prints com- 
plete 96 character ASCII 
font. Complete with inter- 
face for RS232C and 
20/60mA current loop 
mode. Also Centronics 
plug compatible interface 
which accepts data in a 
parallel bit, serial char- 




acter synchronous form. 
Programmable baud rate, 
plus dozens of other fea- 
tures found only in prin- 
ters costing twice as 
much. 



Cat No. 1342 DP8000 Printer $925 

Cat No. 1343 TRS-80 Adapter Cable $40 

Cat No. 1456 3000 sheets 1 part paper $31.50 

Cat No. 1457 1500 sets 2-part paper $40.50 

Cat No. 1458 1000 sets 3-part paper $40.50 



RECTIFIERS & BRIDGES 

Order by Cat No, Voltage, and Current 



1A 


3A 


12A 


35A 


2A 


6A 25A 


RECT. 


RECT. 


RECT. 


RECT. 


BRIDGE BRIDGE BRIDGE 


#1001 


#1002 


#1391 


#1392 


#1003 


#1004 #1034 


50V .05 


.12 


.36 


.80 


.30 


.50 1.20 


1O0V .06 


.16 


.50 


.98 


.45 


.65 1.50 


200V .08 


.20 


.64 


1.15 


.60 


.80 2.00 


400V .10 


.24 


.78 


1.35 


- 


2.50 


600V .12 


.30 


.98 


1.60 






800V .14 




1.26 


1.95 




- 


.10O0V .16 




1.54 


2.30 







SSM 

Available at 
HOBBY WORLD 



|Cat No. 
1408 
1409 
1410 
1400 A 

1401A 

1402 
1405 
1406 
1407 
1425 
1426 
1420 
1422 

1424 
1440 

1433 
1434 



Model 


Price 


SB1 kit 


$150 


SB1 a&t 


$212 


SB1 bb 


$35 


MB6B kit 




450 ns 


$139 


MB6B a&t 


$139 


450 ns 


$183 


MB6B bb 


$26 


MB7 kit 


$325 


MB7 a&t 


$370 


MB7 bb 


$26 


MB3 kit 


$54 


M83 a&t 


$108 


MB4 kit(2MHz)$80 


MB4 a&t 




(2MHz) 


$132 


MB4 bb 


$26 


PB1 kit 




w/textool 


$125 


MB8A kit 


$78 


MB8A a&t 


$125 



Cat No. 
1435 
1436 
1437 
1429 
1430 
1431 
1427 
1428 

1403 
1417 
1418 
1419 
1438 
1439 
1414 
1415 
1416 
1411 
1412 
1413 



Model 
MB8A bb 
MB9 kit 
MB9 a&t 
OB1 kit 
OBI a&t 
OB1 bb 
XB1 

Connector for 
XB1 

CB-1 kit 
VB1B kit 
VB1B a&t 
VB1B bb 
VB2 kit 
VB2 a&t 
■02 kit 
I02 a&t 
I02 bb 
I04 kit 
I04 a&t 
I04 bb 



Price 
$26 
$64 

$118 
$45 
$74 
$26 
$10 

$4 

$119 

$129 

$175 

$26 

$135 

$195 

$48 

$75 

$26 

$139 

$185 

$26 



Ribbon Cable 

CLEARANCE 

SALE 

{•Flat style, 28AWC 
| 'Order by Cat No. 7767 
& conductors 

Cond. 10 ft. 

10 $1.00 

26 2.60 

34 3.40 

40 4.00 



IC Sockets ' 


Penny-A-Pin 


Texas Instruments 


Solder tail 




Package quantities only 


Order by Cat 


No. 1117 and 


pins 




8 pin 


20 for $1.60 


14 pin 


10 for $1.40 


16 pin 


10 for $1.60 


18 pin 


8 for $1.44 


20 pin 


8 for $1.60 


22 pin 


8 for $1.76 


24 pin 


3 for .72 


28 pin 


3 for .84 


40 pin 


2 for ,80j 



/Hatchless Systems - TRS-80 

/Minidisk Drive 



Accesses twice as fast as 
the Radio Shack drive, 
plus offers 40 tracks as 
opposed to 35! Includes 
| case, power supply, and 



cables. Completely assem- 
bled and tested, ready to 
plug in and go! Simple 



$395 



modification to 
second drive! 
Cat No. 1375 MINIDISK 

DRIVE $395 
Cat No. 1396 4 DRIVE 

EXPANSION CABLE $40 
Cat No. 1147 Verbatim Diskettes 
for above - box of 10 for $27 



Send for 

FREE 

CATALOG 

Featuring: 

The best selection of com- 

f mtcr accessories add-ons, 
actory fresh IC's, led's, 
semi's, software, PC aids, 

? prototyping aids, books, 
est equipment, and more! 
Always updated! Dozens 
of new products every J 
Jssue! 



r Pay by check, COD, Visa,' 
or Mastercharge. Order 
by phone or mail. Mini- 
mum order $10. Please 
include phone number and 
magazine/issue you are 
ordering from. USA: Add 
$2 for shipping/handling 

P round; $3 for air. 
OREIGN: Add. $3 for 
surface. $6 for air. COD's 
$1 add'tl. Guaranteed sat- 
isfaction for 120 days or 
your money back! Not re- 
sponsible for typographical 
errors. We reserve the 
l right to limit quantities. 



Dept. B9 NORTHRIDGE, CA. 91324 



Circle 170 on inquiry card. 



BYTE September 1979 227 



POB 

[AMIIHCAN 1 
■ XPRCBS 1 



Electrolabs 

6721, Stanford, Co. 94305 




,„ cw/om/ 415-321-5601 
//»'„- 800-227-8266 
TLX: 345567 



FLOPPY SYSTEMS 



NEW . 

CATALOGUE 



Crystals 

Integrated circuits 

Keyboards 

Lasers 

LSI-11 

Media 

RAMs 

S-1 00 Components 

Z-80 Components 




8" Siemens FDD 120-8 Drive 

All. Siemen's options included 
in this drive which can be con- 
figured hard or soft and single 
or double density. (Others give 
only stripped unit) $399.00 



"Power One" Model CP206 
Floppy Power Unit For two 

drives going full-out, and poss- 
ip ably more on less severe service. 
Wf§ 2.8A@>24V, 2.5A@5V, 0.5A@-5V. 
t J Beautiful quality. $99.00 



DISKETTES (Standard) 



<^ 




8" 

SV" 



Boxed 10 
Boxed 10 



539.00 
534.95 



*^~. 




Tarbell ("It Works") Interface 
(Includes cable set for 2 drives) 
$265.00 BUT ONLY $219.00 
with purchase of two drives. 

Cable Kits 10' with 50 cond. 
cable and connectors and also 
Molex connectors and power 
cable: For one drive: $27.50 
For two drives: $33.95, and 
for three drives: $38.95 



CABINETS for FOD120 and 
801 R Drives, or CP206 power 
supply. Matte finish in mar 
resistant black epoxy paint. 

ng type design. $29.99 




ELECTRO LABS is proud to announce appointment as 
DISTRIBUTOR by CI I- Honeywell Bull. 

PRICE BREAKTHROUGH on SUPERDJSK 10MBY! $3495.00 

General purpose controller (requires 2 parallel I/O ports) 1 500.00 

S- 100 Controller (DMA) 995.00 

"RL-01/RK-05" surrogate 1900.00 

(transparent to RT, RS, RX) 

SOFTWARE: (CP/M Compatible) 

SUPERD0S1 

(Z-80) $695.00 ^ 

MICR0D0S1 

(TRS-80)... $199.00 
Power supply (switching) jL 

$395.00 

Enclosure (desktop) "~"1, ". 

£ 99 00 
* aa,uu Removeable Media Cartridge Drive 






Hi 




Used Sylvania 12" Video Moni- 
tors. Composite video 15mhz, 
115vac, 50/60hz New Tube. As 
shown $109 OEM style without 
case: $99, Anti-glare tube option 
add $12. Specify p4 or p39 

ESAT 200B 



BI-LINGUAL 80x24 
COMMUNICATING 
TERMINAL 
Scrolling, full cursor, bell, 
8x8 metrix, 110-19,200 
baud. Dual Font Appli- 
cations. Arabic & Hebrew, 
Multilingual Data Entry, 



5%" 

MINI-FLOPPY 
DRIVE 
$299.00 



- single or double dens- 
ity - quick access time 

- high reliability & 
durability 



Mini-floppy CABLE KIT: 
for TRS-80 or your 
Tarbell controller. 
$24.95 



Daisy Wheel Printers 
Qume Sprint: 3\45 




Print wheels $8.95 Ribbons $5.95 



OEM Style mechanism $1399.00 





Forms Drawing, Music Instruction, Specialized Graphics (e.g. Games, Chemical Plants, 
Switchyards) $349.00 We carry keyboards, cases, power supplies, etc., enough to make 
an entire system. 



228 BYTE September 1979 



Circle 115 on inquiry card. 



The 



TO ORDER CALL TOLL FREE 800-223-7318 





• 16-bit microprocessor 

• 16K RAM 

• 13" color monitor 
(24 lines of 32 chrs.) 

• 26K BOM opereting system 
(Includes 14K BASIC) 

• Sound - 3 tones. 5 octaves 

• 16 colors: 192 x 256 res. 

• Large Tl library of ROM 
programs available. 



Includes 13"l 
olor Monitor!! 



only 
FINALLY k — — 1$1150 

TEXAS \H»^ 
INSTRUMENTSTI-99/4 
Home Computer 

Many Peripherals. Coming soon! 



APPLE II PLUS ONLY$1195 



A complete sell-contained computer system with APPLESOFT floating point 
BASIC in ROM. lull ASC 1 1 keyboard in a light weight molded carrying case. 

Features Include: 

• auto-start ROM • Hi-Res graphics and 15 color video output. 

• Expandable to 48K. 

Disk $595 Programmer's Aid 50 

Add-on Disk 495 Speechlab 229 

Pascal Card 495 Lightpen 250 

Business Software 625 Communication Card 225 

Monitor 149 Modem 200 

PnnterCard 180 EPROM Programmer 100 

NEW D. C. Hayes MICROMODEM II 

• Combines the capabilities of a communications card and acoustic coupler. 

• Plugs directly into Apple slot and modular telephone Jack. *o^n 

• Auto dial/receiver* FCC approved Only* $379 

NEW Mountain Hardware SUPERTALKER 

• Digitized speech recording and playback. • Must be heard to be believed! 

• Foreign language teaching pack available. • Software compatible. 

only $279 



SUPRBRAIN 



TM 



INTE3TEC 

DATA 

SYSTEMS 

ONLY 

$2995 




d:: : m 




on 



iv $795 



• 14K ROM Operating system 

• 8K RAM Memory 

• 9" Video Monitor 

• Built in Keyboard 

• Digitally controlled tape 



S1 495 Complete! 
16K Model add $200 
32K Model add $500 



PET 




More than an intelligent terminal, the SuperBrain outperforms many other 
systems costing three to five times as much. Endowed with a helty amount of 
available software (BASIC, FORTRAN, COBOL), the SuperBrain is ready to 
take on your toughest assignment. You name it! General Ledger, Accounts 
Receivable, Payroll, Inventory or Word Processing. . .the SuperBrain handles 
all of them with ease. 

Features Include: 

• two dual-density minifloppies with 320K bytes of disk storage 

• 64K of RAM to handle even the most sophisticated programs 

• a CP/M Disk Operating System with a high-powered text editor, 
assembler and debugger. 



FREE 



$35 of Software with purchase 
of any computer on this page. 



COMPUCOLOR II Disk-Based Model 3 
Advanced hardware and software technology 
gives you 

• 13' Color Display 

• Advanced Color Graphics 

• 51K Disk Built-in 

• 16K ROM Operating System 

• 8K RAM User Memory 

• 4K RAM Refresh 

• 8080A Microcomputer 

• RS-232 I/O 



|^t SPECIAL SPECIAL 

$200 FREE Software with,Jy| 
purchase of 8K PET >* | 



Over 1000 software 
tapes, books, disks 
on display. 
Come in and brouse. 



JM Xacc 

V Wf Data General 



BUSINESS 

COMPUTER 

IMSAI 




The low cbsl solution 

lor all small business 

problems A wide varn 

of software is 

available lor ail your needs 

PCS series include dual llopp.es. 32K RAM. 

I O. DOS. BASIC 

• PCS-42 (400KB) $3295 

• PCS-44 (780KB) $3995 

VDP-42 series adds video terminal, key- 
board and VIO to above 

• VDP-42 $4995 • VDP-44 $5595 

• VOP 80 $7995 • VDP 180 $8995 



10 Megabyte 
System $17,040 



DATA GENERAL 
^ micro NOVA 

The ultimate in small 
Business Computers 
when matched with 
COMPUTER FACTORY'S 
inicomputer. Software: 
Accounts Receivable/Payable, 
Inventory Control/ Order Entry. 
Genreal Ledger, Payroll Systems. . . . 
from $12,140 for 64K computer 
with cabinet, printer terminal, video terminal. 
dual disk and mutll-user operating system! 



SOUNDWARE 

MUSIC BOX 



only $29.95 



Music and Sound Effects for PET, TRS-80. 
& Compucolor ll Add music and sound effects to 
your programs. Compose, play, and hear music 
on your computer. Completely self-contained. 
Free programs. 




This fantastic program disk allows the statistician, 
Moving mathematician, trader in stocks, money or 

Average commodities, the ability to maintain 30 database 
Plot series of up to 300 values and plot 3 different moving 

Program averages of a series at the same time, in 3 different 
FOR colors. Files can be updated, deleted, changed, 

APPLE extended, etc. 

A sure value disk at only $40! 

Word Processing For Apple on disk.. .$50 




■ £4 User Defined Cher 

• 240 » SI? Resolution Grai 

Module! dtugn al 

lor program* end RDM PAC 

luture language i 

COBOL. PILOT. FORTRAN. 



8KS 995 
16K$1145 
32K $1295 
48K $1445 



SORCERER 

SPECIAL 
12 Video Monitor 
> for SORCERER 
($299 value) 

ONLY 

125 with 8K unit 
95 with 16K unit 
65 with 32K unit 



ANDERSON JAC0BS0N 




S41 1/0 Terminal 
Ideal (or word procei 



mg end imall bun 



• ASC 11 Code 

• 15 cot Printout 

• High Quality Selective Printing 

• Use Keyboard tot PET 

• Retiebte heavy duty Mechanum 

• Completely Refurbished by A.J. 

• Service in 15 Major CitiM 



foCKII 



NOW IN s 

Parallel 

$1095 



$1195 



RADIO SHACK • PET • SORCERER 
|APPLE • COMPUCOLOR • ETC. 



PRINTERS • PRINTERS • PRINTERS 



The COMPUTER FACTORY'S extensive CENTRONICS 779 $ 945 

inventory and wide seler.lion of computer TRENDCOM 100 375 

printers assures you of finding the printer TRENDCOM 200 N/A 

best suited for your needs and INTEGRAL DATA 795 

specifications The following printers work DIABLO/XEROX 2695 

well with all known personal computers COMPRINT 560 



Min Credit Card 
Order $75 



VISA* 



Open 
Mon.-Fri. 
10-6 



NY restdnnis add 8°'6 sales lax • Same day Cat 1fl A 
shipment on prepaid and credit card orders ***"■ I"-** 
• Add S5 shipping lot computers. $3 for 
boards. $1 each cassette fape. 




NEW 
CENTRONICS 730 

50 CPS ■ MICROPROCESSOR 
CONTROLLED! 

Tractor & Friction Feed • Uses 
Single Sheets, Roll, Fanfold • Upper 
& Lower Case • Light Weight 

Parallel $995 
Serial $1045 






«&>*£& 



TO ORDER CALL TOLL FREE 800-223-7318 



vH» 



o^ 



iW 






TLft fVMUIDI ITCD CAPTHDV 485 Lexinqton Avenue 750 Third Avenue Mew York. N.Y. 10017 
I lit? V-fWlVIn U I Cn TMV^ I \JT\ I (212) 687-5001 (212) PET-2OOI Foreign order desk ■ Telex 640U55 



BYTE September 1979 229 




computer 
products, inc. 



11542-1 KNOTT STREET 

GARDEN GROVE, CALIFORNIA 92641 

(714) 891-2663 



MICROBYTE Z80/I-O 



• A complete single board Z60A 
CPU and serlal/paralle I/O system 

• Fully S-100 Bus compatible, 
IMSAI, ALTAIR 

• Z80A CPU (4 MHz version of the 
280) 

• 158 Instructions — superset of 
and upward compatible from the 
8080's 78 Instructions 

• Provision for up to 4K on board 
monitor program using 1K (2708), 
2K {2716), 4K 2732 

• On board EPROM can be hard- 
ware and/or software deselected 

• 2 MHz or 4 MHz operation is 
switch selectable 

• or 1 wait state for all cycles is 
switch selectable 

• 2 RS-232C serial ports with 8251 
USARTs 

• Serial baud rates switch 
selectable 

• 24 programmable parallel I/O 
lines (uses 8255) 



Gold Contacts for higher relia- 
bility 

Power requirements: + 8V ® 
800mA, + 16V, @ B6mA, - 16V 
@ 100mA 

X" rating temperature 0*-55"C 
operate with or without 
IMSAI/ALTAIR front panel 
' Low power shottky tri-state buf- 
fers on all address and data lines 
1 Fully warranted for 120 days from 
date of shipment 




$325. ( 



IMSAI CONN. 

100 PIN-SOLDERTAIL 
GOLD CONTACTS 

$3. 00 each or 10/2.60 each 



8251 

PROGRAMMABLE/U-ART 
TESTED® 4 MHZ 

$5. 00 each 



TRS-80 



Floppy disk drive with 
cabinet & pwr. supply 
compatible with Radio 
Shack Interface. Ass- 
embled & tested with 
1 yr. warranty on 
parts & labor. 

Mfg. by Lobo Drive 




$385 



Interface Cable Available 



SPECIAL 

.1 @ 12 VOLTS 
CERAMIC CAP 

10$ each 
or 

100/$9. 00 



MICROBYTE 16K STATIC RAM BOARD 



Fully S100 Bus Compatible, 

IMSAI, SOL, ALTAIR, ALPHA 

MICRO 

Uses National's Low Power 5257 

4K x 1 Static Rams 

2 MHz or 4 MHz operation 

On board single 5 amp regulator 

Thermally designed heat sink 

(board operating temperature a 

- 70*C) 

Inputs fully low power Shottky 

Schmitt Trigger buffered on all 

address and data lines 

1 Phantom Is jumper selectable to 
pin 67 

Each 4K bank addressable to any 
4K slot with in a 64K boundary. 
4K hardware or software select- 
able 

< Selectable port address 
4K banks can be selected or dis- 
abled on power on clear or reset 



Will operate with or without front 
panel 

Compatible with ALPHA MICRO, 
with extended memory manage- 
ment for selection beyond 64K 
No DMA restriction 
Low power consumption 1.3 amp 
Fully warranted for 120 days from 
date of shipment 
Extended addressing up to 1 
megabyte of addressable ram 




450 NS $320.°° 
300 NS $340. 00 



MICROBYTE 32K STATIC RAM BOARD 



• Fully S1O0 Bus Compatible, 
IMSAI, SOL, ALTAIR, ALPHA 
MICRO 

• Uses National's Low Power 5257 
4K x 1 Static Rams 

• 2 MHz or 4 MHz operation 

• On board single 5 amp regulator 

• Thermally designed heat sink 
(board operating temperature 0* 
- 70"C) 

• Inputs fully low power Shottky 
Schmitt Trigger buffered on all 
address and data lines 

• Phantom Is Jumper selectable to 
pin 67 

• Each 4K bank addressable to any 
4K slot with In a 64K boundary. 

• 4K hardware or software select- 
able 

• One on board 8-bit output port 
enables or disables the 32K In 4K 
blocks 

• Selectable port address 

• 4K banks can be selected or dis- 
abled on power on clear or reset 



• Will operate with or without front 
panel 

• Compatible with ALPHA MICRO, 
with extended memory manage- 
ment tor selection beyond 64K 

• No DMA restriction 

> Low power consumption 2.3 — 
2.5 amps 

• Fully warranted for 120 days from 
date of shipment. 

Extended addressing up to 1 
megabyte ol addressable ram 




450NS$620. 00 
300NSS650. 00 



MICROBYTE MOTHERBOARD 



• Extra wide ground plane 

• Silk screen and solder mask 

• Assembled and tested 



> Active Diode termination 

> Slot for IMSAI front panel 
• Terminal block connection for 

easy hook-up 

9 slot kit $70. 00 A&T$100. 00 
20 slot kit$125. 00 A&T$155. 00 
Bare Board 9slot$30. 00 20 slot $50.°° 



MICROBYTE DISK CONTROLLER 



• IBM 3740 Soft Sectored 'Compat- 
ible 

• Z80 or 8080 compatible on S-100 
Bus 

• Single density runs both mini and 

full size drives, runs CPM, on 
Shugart, Perscl, Memorex etc. 

• Selectable port/address 

• On board 2708/2716 for bootstrap 
or monitor program 

• No hardware jumpers, uses plug 
in modules for different drives 

• Uses 1771 B-Qt controller chip 

• Assembled and tested 

• Specify disk drive used when 
ordering by mail 




$225.° 



SHUGART 

801-Disk Drive 

WITH CABINET & POWER SUPPLY 

ASSEMBLED & TESTED 

1 YR PARTS & LABOR 

Mfg, by Lobo Drive 

$585. 00 

Dual Cabinet & Drives Available 



2708's 

LOW POWER 
450 NS. 

$8. 75 each 
8for$66. 00 



SHUGART 

SA400 



DISK DRIVE INCLUDES CABINET. NO PWR 

SUPPLY, CUTOUTS FOR SWITCH, FUSE, & 

INTERFACE CABLE 

Mlg. by Lobo Drive 
00 



2716 

5 VOLT ONLY 

LOW POWER 

450 ns 



$325. 



$40. 



00 



SCANBE/RN 

SOCKETS -LO PROFILE 

(tin) 
1-24 25-99 100-499 500 up 



REGULATORS 



14 PIN 


.16 


.15 


.14 


.12 


16 PIN 


.17 


.16 


.15 


.14 


18 PIN 


.20 


.19 


.18 


.16 


20 PIN 


.29 


.28 


.26 


.25 


24 PIN 


.34 


.32 


.30 


.28 


40 PIN 


.60 


.58 


.56 


.52 



1-9 10-49 50UD 



320 T- 5 
320T-12 
340 T5 
340 T- 12 
78H05 



1.25 
1.00 

.75 

.75 

6.00 



1.15 
.90 
.70 
70 

5.70 



1.05 
.85 
.65 
65 

5.40 



NEW PRODUCTS 

8086 — CPU BOARD 

8088 — CPU BOARD 

Double Density Controller 

CALL OR WRITE 
FOR DEALER INFO 



CABLE 
ASSEMBLY 

for 8" disk drives 

(2) 50 PIN CARD - 

EDGE CONNECTORS 

ON 4ft. RIBBON 

CABLE 

$20. 00 ea. 

extra conn. $7. 00 ea. 



ORDERING INFORMATION: 

Name, Address, Phone 

Ship by: UPS or P.P. 

Shipping Charge: Add $2.50 up to 
5 lbs., all excess shipping 
charges will be refunded. Credit 

cards will be charged appropriate 
freight. 



TERMS: 

We accept cash, check, money 
orders, Visa, and Master Charge 
cards. (U.S. Funds Only). 
COD's: on approval only 
Open Acct's: companies may 

inquire for net terms. 
Tax: add 6% for Calif, residents only 



230 BYTE September 1979 



Circle 11 on inquiry card. 



Circle 230 on inquiry card. 



wmam California computer systems 

16K RAM BOARD. Fully buffered addressable in 4K 
blocks. IEEE standard for bank addressing 21 14's 

PCBD $26.95 

Kil 450NSEC $259.95 

PT-1 PROTO BOARD. Over 2,600 holes 4" regu- 
lators. All S-100 buss functions labeled, gold fingers. 
PCBD $25 95 

PT-2 PROTO BOARD. Similar to PT-1 except set- 
up to handle solder tail sockets. 
PCBD $25.95 

sSffl 

FORMERLY CYBERCOM/SOUD STATE MUSIC. 

PB-1 2708&2716 Programming Board with provisions 
for 4K or 8K EPROM. No external supplies require 

textool sockets. Kit $124.95 

CB-1 8080 Processor Board. 2K of PROM 256 BYTE 
RAM power on/rest Vector Jump Parallel port with 

status Kil $119.00 PCBD $30.95 

MB-6B Basic 8KX8 ram uses 2102 type rams, S-100 

buss. Kit 450 NSEC ...$139.95 PCBD $26.95 

MB-7 16KX8, Static RAM uses U.P410 Protection, 

fully buffered Kit $299.95 

MB-8A 2708 EROM Board, S-100, 8K8X or 16Kx8 

kit without PROMS $75.00 PCBD $28.95 

MB-9 4KX8 RAM/PROM Board uses 2112 RAMS or 
82S129 PROM kit without RAMS or PROMS $72.00 
IO-2 S-100 8 bit parallel /IO port, % of boards is for 

kludging. Kit $46.00 PCBD $26.95 

IO-4 Two serial I/O ports with full handshaking 
20/60 ma current loop: Two parallel I/O ports. 

Kit $130.00 PCBD $26.95 

VB-1B 64 x 16 video board, upper lower case Greek, 
composite and parallel video with software, S-100. 

Kit $125.00 PCBD $26.95 

Altair Compatible Mother Board, 11 x 11 Vi x Vt" . 

Board only $39.95. With 15 connectors $94.95 

Extended Board full size. Board only $ 9.49 

With connector $13.45 

SP-1 Synthesizer Board S-100 

PCBD $42.95 KIT $135.95 



W7nC // ne WAMECO INC. 



FDC-1 FLOPPY CONTROLLER BOARD will drive 
shugart, pertek, remic 5" & 8" drives up to 8 drives, 
on board PROM with power boot up, will operate 
with CPM (not included). 
PCBD $42.95 

FPB-1 Front Panel, IMSAI size, hex displays. Byte, 
or instruction single step. 

PCBD .-. $47.50 

MEM-1 8KX8 fully buffered, S-100, uses 2102 type 

rams. PCBD $25.95 

QM-12 MOTHER BOARD, 13 slot, terminated, S-100 

board only $34.95 

CPU-1 8080A Processor board S-100 with 8 level 

vector interrupt PCBD $26.95 

RTC-1 Realtime clock board. Two independent in- 
terrupts. Software programmable. PCBD $23.95 

EPM-1 1702A 4K Eprom card PCBD $25.95 

EPM-2 2708/2716 16K/32K 

EPROM CARD PCBD $25.95 

QM-9 MOTHER BOARD, Short Version of QM-12. 

9 Slots PCBD $30.95 

MEM-2 16K x 8 Fully Buffered 

2114 Board PCBD $26.95 



80B0A $9.95 

8212 2.49 

8214 4.49 

8224 3.49 

2708 9.49 

5101-1P 6.90 



5101-8P $ 8.40 

2114 (450 NS) lowpwr ... 7.25 
2114 (250 NS) lowpwr... 7.99 

2102A-2L 1.50 

2102A-4L 1.20 

4116 8/89.95 



M 




(415) 592-1800 
P. O. Box 424 • San Carlos, California 94070 

Please send for IC, Xistor 
and Computer parts list 



SEPT SPECIAL SALE 
ON PREPAID ORDERS 

(charge cards not included on this offer) 

8KX8 RAM Fully buffered 450 NSEC. 
2.5 amp typical assembled parts may 
be unmarked or house numbered. 
$99.99 

MIKOS PARTS ASSORTMENT 
WITH WAMECO AND CYBERCOM PCBDS 

MEM-2 with MIKOS ~7 16K ram 

with L2114 450 NSEC $249.95 

MEM-2 with MIKOS =13 16K ram 

with L2114 250 NSEC $279.95 

MEM-1 with MIKOS #1 450 NSEC 8K 

RAM $119.95 

CPU-1 with MIKOS #2 8080A CPU $94.95 

MEM-1 with MIKOS #3 250 NSEC 8K 

RAM $144.95 

QM-12 with MIKOS #4 13 slot mother 

board $89.95 

RTC-1 with MIKOS #5 real time clock $54.95 

EMP-1 with MIKOS #10 4K 1702 less 

EPROMS $49.95 

EPM-2 with MIKOS #11 16-32K EPROMS 

less EPROMS $59.95 

QM-9 with MIKOS #12 9 slot mother 

board $79.95 

FPB-1 with MIKOS =14 all parts 

for front panel $134.95 

MIKOS PARTS ASSORTMENTS ARE ALL FACTORY PRIME 
PARTS. KITS INCLUDE ALL PARTS LISTED AS REQUIRED 
FOR THE COMPLETE KIT LESS PARTS LISTED. ALL SOCKETS 
INCLUDED. 

VISA or MASTERCHARGE. Send account number, interbank 
number, expiration date and sign your order. Approx. postage 
will be added. Check or money order will be sent post paid in 
U.S. If you are not a regular customer, please use charge, 
cashier's check or postal money order. Otherwise there will 
be a two-week delay for checks to clear. Calif, residents add 
6% tax. Money back 30 day guarantee. We cannot accept re- 
turned IC's thai have been soldered to. Prices subject to 
change without notice. $10 minimum order. $1.50 service charg* 
on orders less than $10.00. 



W03 
4007 ■ 
4000 - 



C/MOS (DIODE CLAMPED) 

4033 - 22 4069 - .45 

4024 - 

4026 - 

4017 - 

4028 - 

4079 - 

4030 - 

4036 - 



4D72 - 

451 a - 

4520 - 



4042 



4063 - 
40GS - 
4066 - 



74C02 - 
74C08- 
74C1Q- 
74C20- 
74C42- 
74C73- 



70 74C90- 



74C15I - 
74C157 - 
74C160 - 
74C16S - 
74C173 - 
74CI74 - 
74CI75- 
74CI03- 
74C901 - 
74C90! - 
74C914 - 



3623 STATIC SHIP 



IS-3409 Wl BO BITS □YN.5I' 



1.9S B3E23 - 
17 95 BJSIZ9 



US AY61013 VAHT - 

35« TR1 «HB - 

M B703CTELEDYNEB 

3*5 n l«B3 fl PSAT - 

1.95 90S0A - 

2 *5 BZ ,b _ 



-CRYSTALS $3.45 •« 

2.000 MHz 6.144 MHz 
4.000 MHt. 8.000 MHz 
3.57 MHz 10.000 MHz 
5.000 MHz 20.000 MHz 
6.000 MHz 



RIBBON CABLE 
PLAT (COLOR CODED) 
#30 WIRE 
26 cond. - .S0/per foot 
40 cond. ■ ,75/pcr foot 
50 cond. • .90/oor foot 



CTS 206-8 eight position dip switch $1.60 

CTS 206-4 four position dip switch $1.45 

LIGHT ACTIVATED SCR's to 18. 200 ,V 1A. .$.70 

SILICON SOLAR CELLS 
4" diameter .4V at 1 AMP $10.00 

FND 359 C.C.. 4" $.60 LED READOUTS 
FCS8024 4 digit DL-704 C.A. .3" $ .75 

C.C 8" display 55.95 DL 747 C.A. 6" $150 
FND503C.C. .5" S .85 HP3400 .8"CC $1.95 
FND 510 C.A. .5"$ .85 HP3405 ,8"CA $1.95 
DL 704 .3" C.C. S 85 



PRINTED CIRCUIT BOARD 



7WATTLD 65 LASER DIODE I R Sa95 



2N 3820 P FET S 45 

2N 5457 N FET $ 45 

2N2646.UJT S .45 

ER 900 TRIGGER DIODES 4 SI 00 

?N G028 PROG UJT 5 65 

MINIATURE MULTI-TURN TRIM POTS 
100, 1K, 2K, 5K, 10K. 20K, 50K, 
200K, 1Mcrj, 2Mcg, 5.75 each 3/S2.00 

25 watt Infra Red Pulse I SG 2006 Bquiv. ) 
Laser Diode (Spec sheet included) S24.95 

V E RIPAX PC BOARD $ 12.95 

Our new Prototyping is a hi density 4M" x 6V1" 
single sided 1/16" epoxy board. It will hold 40, 
24, 16 (34 units). 14 + 8 pin IC's. There are 
three busses, + 5V, ground and a Moating buss. 
There is a pad for a TO-220 regulator. There is a 
22 pin edge connector with . 1 56" spacing. 

FP 100 PHOTO TRANS S .50 

RED, YELLOW, GREEN 

LARGE LED's. 2" 6/$l .00 

TIL-118 0PTO-ISOLATOR $.75 

MCT-6 OPTO ISOLATOR S .80 

1 WATT ZENERS: 3,3, 4.7, 5.1, 5.6, 9.1, 

10, 12, 15, 18, or 22V 6/41.00 

MCM 6571A 7x9 character gen . . S 10.75 , 

UNIVERSAL 4Kx8 MEMORY BOARD KIT 
$69.95 

32-2102-1 fully buffered, 1G address linos, on 
board decoding for any 4 of 64 pages, standard 
44 pin buss, may be used with F-8 & KIM 



Silicon Power Rectifiers 



10.50 16.50 



1 7 50 20.00 



SAD 1024 a REDJCON 1024 sioge a 



IN 4148 <IN91< 
.1 uf 25V ceran 



RS232 DB 26P mala $2 95 

CONNECTORS DB 255 female . . S3. 50 

HOODS .' $1.50 



REGULATORS 



323K - 5V 3A . 

309K 

723 . 
320T- 

5, 12, or 15 V 



TRANSISTOR SPECIALS 

2N6233-NPN SWITCHING POWER $ 1.95 
MRF-B004 a CB RF Transistor NPN $ -75 

2N3772 NPN 5i TO 3 . . . $ 1.00 

2N1546 PNP GE TO-3 $ .75 

2N4908 PNP Si T0 3 S I 00 

2N5086 PNP Si TO 92 . . 4 S 1 .00 

2N3137 NPN Si RF $ .55 

2N3919 NPN S. TO-3 RF S 1.50 

2N1420NPNSiTO5 3/$ 1.00 

2N3 767 NPN Si TO 66 . . . S .70 

2N2222 NPN Si TO 18 . 5 S 1.00 

2N3055 NPN Si TO-3 S 60 

2N3904 NPN Si TO-92 6/S 1.00 

"2N3906 PNP Si TO 92 . 6/4 1.00 

2N5296 NPN Si TO 220 . S 50 

2N6109 PNP Si TO-220 ... S 55 

2N3fi38 PNP Si TO 5 55 1.00 

MPSA 13 NPN Si 4/$ 1 .00 



TTLtC SERIES 



M42 



4150 - 



J--.J"< 



Si 



»*5 .97 7*161 - 91 743GB - 93 

'»*! - S' 74153 - 3! 74393 - 1.B7 

744G - 107 76327 - 2.26 74339 - 2 25 

DATA CA5SETTES 1/2 HR $.95 *" 
14 pin headers 3/41.00 

MM5387AA . . . CLOCK CHIPS ■ ■ ■ . $5,95 

M7001 47.50 

MM5369 $3.75 

no. 30 wire wrap wire single 
^^rant^^^ioo/sujq^^^^^ 

alco miniature toggle switches 
mta 106 spot s .95 

MTA 206 DPDT 5 1 .70 

MTA 206 P-DPDT CENTER OFF * -\ 85 

MSD 206 P-DPDT CENTER OFF 

LEVER SWITCH $ 1.85 



6A 



1.32 



1.92 



4.40 



DIP SOCKETS 

fl PIN .17 24 PIN ,35 

14 PIN .20 28 PIN 40 

16 PIN ,22 40 PIN .60 
18 PIN .25 



SANKEN AUDIO POWER AMPS 

Si 1010 G 10 WATTS $ 7.80 

Si 1020 G 20 WATTS $15.70 

Si 1 050 G 50 WATTS $28.50 



TANTULUM CAPACITORS 



.22UF 35V 5/41.00 
.47UF 35V5/$1.00 
.68UF 35V5/$1.00 
1UF 35V 5/41.00 
2.2UF20V5/4t.00 
3.3UF 20V 4/41.00 
4.7UF 15V 5/41.00 



6.8UF 36V 4/41.00 

10UF 10V $.25 

22UF 25V $ .40 

15UF 35V 3/S1.00 

30UF 6V 5/41.00 

150UF 15V $ .95 

68 UF 15V S .50 



7Us SERIES 



LINEAR CIRCUITS 

LM 201 -.75 
IM30W74B 35 
LM307 - .30 
LM 308 - 75 
LM311 - 75 
LM3I8 -1.20 

LM 324 -.95 



LM 380 
LM 363 
LM386 
LM 387 




Circle 340 on inquiry card. 



BYTE September 1979 231 



7400 TTL 



SNMOON 
SN7401N 
SN7402N 
SN7403N 
SN7404N 
SN7405N 
SN7406N 
SN7407N 
SM74D6M 
SN7409N 
SN7410N 
SN7411N 
SN7412N 
SN7413N 
SN7414N 
SN7416N 
SN7417N 
SN742QN 
SN7421N 
SN7422N 
SN7423N 
SN7425N 
SN7428N 
SN7427N 
SN7429N 
SN7430N 
SN7432N 
SN7437N 
SN7438N 
SN7439N 
SN744QN 
SN7441N 
SN7442N 
SN7443N 
SN7444N 
SN7445N 
SN7446N 
SN7447N 
SN7448N 
SN745QN 
SN7451N 
SN7453N 
SN7454N 
SN7459A 
SN7460N 



CD4000 
CD4001 
CD4002 
C04006 
C04007 
CD40O9 
C04010 
CD4011 
CD4012 
CD4013 
C04Q14 
CD4015 
C04016 
CD4D17 
CO4018 
C04019 
CD402O 
CD4021 
CD4022 
CD4Q23 
C04024 
CO4025 
CD4D26 
CD4027 



74CO0 
74C02 

74C04 
74C08 
74 CIO 
74C14 
74C20 
74C30 
74C42 
74C4B 
74C73 
74C74 



6.50 



7BMG 1.75 

LM106H .99 

LM300H .60 

LH301CN/H .35 

LM302H .75 

LM304H 1.00 

LM305H .60 

LM307CN/H .35 

LM308CN/H 100 

LM309H 1.10 

LM309K 1.25 

LM310CN 1.15 

LM311N/M .90 
LM312H 
LM317K 
LM31BCN/H 

LM319N 1.30 

LM320K-5 1 35 

LM320K-5.2 1.35 

LM320K-12 1.35 

LM32QX-15 1.35 

LM320K-1B 1.35 

LM320K-24 1.35 

LM320T-5 1.2S 

LM320T-S.2 1.25 

LM320T-8 1.25 

LM32QT-12 1,25 

LM320T-15 1.25 

LM320M8 1.25 

LM320T-24 1,25 

LM323K-5 5.95 

LM324N 1.60 

LM339N .99 

LM340K-5 1 35 

LM34QK-G 1.35 

LM340K-8 135 

LM340K-12 1.35 

LM340K-15 1.35 



74LS0O 
74LS01 
74LS02 
74LS03 
74LS04 
74LS05 
74LS08 
74LS09 
74LSI0 
74LS11 
74LS13 
74LS14 
74LS15 
74LS20 
74LS21 
74LS22 
74LS26 
74LS27 
74LS28 
74LS30 
74LS32 
»4LS37 
74L540 
1741842 



.29 



SN747QN 
SN7472N 
SN7473N 
5N7474N 
SN7475N 
SN7476N 
SN7479N 
SN74B0N 
SN7482N 
SN7483N 
SN74B5N 
SN7486N 
SN7489N 
5N7490N 
SN7491N 
SN7492N 
SN7493N 
SN7494N 
SN7495N 
SN7496N 
SN7497N 
SN74100N 
SN74107N 
SN74109N 
SN74116N 
SN74121N 
SN74122N 
SN74123N 
SN74125N 
SN74126N 
SN74132N 
SN74136N 
SN74141N 
SN74142N 
SN74143N 
SN74144N 
SN74145N 
SN74147N 
SN7414BN 
SN74150N 
SN74151N 
SN74152N 
SN74153N 
5N74154N 
SN74155N 
SN74156N 
SN74157N 



C/MOS 



CD4028 
CO4029 
C04030 
CO4035 
C04Q40 
CD404I 
C04042 
CD4043 
C04044 
CD4046 
CD4047 
CD* 048 
C04049 
CD405O 
C04051 
CD4053 
CD40S6 
CD4059 
CD4060 
C04066 
CD4068 
C04069 



74C00 



74C8S 
74C90 
74C93 
74C95 
74C107 
74C151 
74tl54 
74C157 
74C160 
74Q61 



LINEAR 

LM340K-18 1.35 

LM340K-24 1.35 

LM340T-5 1.25 

LM340T-6 1.25 

LM340T-8 1.25 

LM340T-12 1.25 

LM340T-15 1.25 

LM340T-18 1.25 

LM340T-24 1.25 

LM358N 1.00 



LM370N 

LM373N 

LM377N 

LM380N 

LM380CN 

LM381N 

LM382N 

NE501N 

NE510A 

NE529A 

NE531H/V 

NE536T 

NE540L 

NE544N 

NE550N 

NE555V 

NE556N 

NE56GB 

NES61B 

NE562B 

NE565N/H 

NE566CN 

NE567V|H 
NE570N 
IM7D3CN/H 
LM709N/H 



1.95 
3.25 



1.79 

B.CO 
600 
4.95 
3.95 
6.00 
6.00 



74LS00TTL 

74LS47 .89 

74LS51 .29 

74LS54 .29 

74LS55 .29 

74LS73 .45 

74LS74 .45 

74LS75 .59 

74LS76 .45 

74LS78 .49 

74LS83 .89 

741S85 1.25 

74LS86 .45 

74LS90 .59 

74LS92 .75 

74LS93 .75 

74LS95 .99 

74LS96 1.15 

74LS107 .45 

74LS109 .45 

74LSI12 .45 

74LS123 1.25 

74LS12S 89 

74LS132 99 

74LS136 .49 



SH74160N 


89 


SN74161N 


.89 


5N74162N 


1.95 


SN74163N 


.69 


SN74164N 


.69 


SN74165N 


,69 


SN74166N 


1.25 


SN74167N 


1<1S 


SN74170N 


1.59 


SN74172N 


600 


SN74173N 


1?5 


SN74174N 


.69 


SN74175N 


.79 


SN74176N 


79 


SN74177N 


.79 


SN74179N 


1.95 


5N74180N 


,79 


SN741B1N 


195 


SN74182N 


.79 


SN741B4N 


1.95 


SN74IB5N 


1.95 


SN741B6N 


0.95 


SN741B8N 


3.95 


SN74190N 


1.25 


SN74191N 


1?S 


SN74192N 


.79 


SN74193N 


.79 


SN74194N 


,89 


SN74195N 


m 


SN74196N 


.69 


SN74197N 


m 


SN7419BN 


1.49 


SN74199N 


1.49 


SN74S200 


4.96 


SN74251N 


1,79 


SN74279N 


.79 


SN74283N 


2.25 


SN74284N 


3 95 


SN742B5N 


3.95 


SN74365N 


.69 


5N74366N 


69 


SN74367N 


.69 


SN74368N 


.69 


SN74390N 


1.95 


SN74393N 


1.95 



CD4070 

C04071 

CD4072 

C04076 

CD4081 

CD4082 

CD4093 

CD4098 

MC14409 

MC14410 

MC14411 

MC14419 

MC14433 

MC14506 

MC14507 

MCI 4562 

MCI 4583 

C045OB 

C04510 

CD451 1 

C04515 

C04518 

CD4520 

CD4566 



74C163 
74C164 
74C173 
74C192 
74C193 
74C195 
74C922 
74C923 
74C925 
74C926 
BOC95 
80C97 



1.50 



LM710N .79 

LM711K .39 

LM723N/H .55 

LM733N 1.00 

LM739N 1.19 

LM741CN/H .35 

LM741-14N .39 

LM747N/H .79 

LM748N/H .39 

LM1310N 2.95 

1.MN5DCN/II .59 

MC148BN 1.39 

MC14B9N 1 39 

LM1496N .95 

LM1556V 1.75 

MC1741SCP 3.00 

LM2111N 1.95 

LM2901N 2.95 

LM3053N 1.50 

LM3065N 1.49 
LM3900N(3401).49 

LU3905N .89 

LU3909N 1.25 

MC5556V .59 

8038B 4.95 

LM75450N .49 

75451CN .39 

75452CN 39 

75453CN .39 

75454CN' .39 

75491CN .79 

75492CN .89 

75493N .89 

75494CN .89 

RC4136 1.25 

RC4151 2.85 

HC4194 5.95 

RC4195 4.49 



74LS13B 
74LS139 
74LS151 
74 LSI 55 

74LS157 
74LS160 
74LS161 
74LS162 
74LS163 
74LS164 
74LS175 
74LS181 
741S190 
74LS191 
74LS192 
74LS193 
74LS194 
7aS195 
741S253 
74LS257 
74LS258 
74LS260 
74LS279 
74LS367 
74LS368 
74LS670 



EXCITING NEW KITS 

a JE600 HEXADECIMAL 
ENCODER KIT 

FEATURES: 

• Full 8 Dil latdied oulpui lot micio- 
procassoi use 

• 3 Usif Define keys wiih one being bl- 
si able ope i a! i on 

• Deoounce nrnnt nrovided lor all 19 



Digital 
Thermometer Kit 



~M 

" I ^H * LED reaOooi to verify entries 

^^^^1 • Easy interlacing with standard 

1C connector 

• Only +5VDC requtiert lot oneiations 

FULL 6 BIT LATCHED OUTPUT— 19 KEYBOARO 

The JE600 Encoder KeyboarrJ provides (wo separate hexadecimal 

digits produced Irom sequential key entries io allow direct prorj- 

ramming lor B oil microprocessor or B bit memory circuits. Three 

(3) additional keys are provided for user operations wrth one having 

a bistable output available The outputs are latched and monitored 

with LEO readouts. Also included is a key entry strobe 

JE600 $59.95 

Hexadecimal Keypad only $10.95 




-•witching control for In- 



■ Ougl tentor 

door/outdoor .. . 
•Continuous LEO .8" hi. display 
•Range: -40 D F to 199°F / -40^ to 1O0°C 
•Accuracy: ±1° nominal 
•Set for Fahrenheit or Celsius reeding 
■Sim. walnut case - AC wall adapter incl. 
• Size: 3-1/4"Hx6-5/8"Wx1-3/8"D 



JE300 $39.95 



DISCRETE LEDS 



.200' Hi 
XC556R red 
XC556G green 
XC556V yellow 
XC55BC cleat 

.200" dil 
XC22R red 
XC22G green 
XC22Y yellow 

.no- mi. 

MVIOB red 4 

.015- die. 
MV50 red 6 

INFRA-RED LED 

1/4"«IM-x1/t6-|M 
5/S1 



sat 
Mi 

4/SI 
4/S1 

5;SI 
Ml 

4/SI 



.121- nil. 

XC209R red 
XC209G green 
XC209V yellow 

.1(5- dil. 
XC526R red 
XC5266 green 
XC526Y yellow 
XC526C clear 

.110- die. 
XC1IIR red 
XC111G green 
XC11IV yellow 
XC1I1C clear 



5,S1 
4/11 
4/SI 

5/S1 
4/J1 

4/SI 
4/SI 

5/S1 
4/SI 

4/S1 
4/SI 



DISPLAY LEDS 



TIMEX T1D01 

LIQUID CRYSTAL DISPLAY 

CUSS II 

FIELD EFFECT 




4 DIGIT - .5' - CHAHACTERS 

THREE ENUNCIATORS 

2.00" X 1.20" PACKAGE 

INCLUDES CONNECTOR 

TIOOl-T.ansmiiiivg S7.9S 

TIOOIAfltflactivs 8.2S 



TYPE 

MAN 1 
MAN 2 
MANS 
MAN 4 
MAN7G 
MAN7Y 
MAN 72 
MAN 74 
MAN 82 
MAN 84 
MAN 3620 
MAN 3530 
MAN 3640 
MAN 4610 
MAN 4540 
MAN 4710 
MAN 4730 
MAN 4740 
MAN 4510 
MAN 4840 
MAN 6610 
MAN 6630 
MAN 6640 
MAN 6650 
MAN 6660 
MAN66S0 
MAN 6710 



KIIJUIITY I 

Common Anode-red 
5 x 7 Dot Maihx-red 
Common Calhode-red 
Common Cathode -red 
Common Anode-green 
Common Anode -yellow 
Common Anode -red 
Common Calhode-red 
Common Anode -yellow 
Common Cathode -yellow 
Common Anode-orange 
Common Anode-orange » 1 
Common Calh ode -orange 
Common Anode -orange 
Common Cathode -orange 
Common Anode-red 
Common Anoda-red ± 1 
Common Cathode -red 
Common Anode-yellow 
Common Cathode -ye How 
Common Anode -orange-D 
Common Anode-orange ^ 1 
Common Calhode-orange-0 0. 
Common Cathode -orange t 1 
Common Anode-orange 
Common Cathode -a range 
Common Anode-rod-u.D. 



TYPE 

MAN 6730 

MAN 6740 

MAN 6750 

MAN 6760 

MAN 6780 

DL701 

OL704 

DL707 

DL728 

DL741 

DL746 

DL747 

0L749 

0L750 

DL33B 

FNO70 

FN0358 

FN0359 

FND503 

FNO507 

5082-7730 

HOSP-3400 

HDSP-3403 

5082-7300 

5082-7302 

5082-7304 

5O62-7340 



POUfllTY 

Common Anode-red ± 1 
Common Calhode-red-D 
Common Cathode-red t 1 
Common An ode -red 
Common Cathode -red 
Common Anode-rod = 1 
Common Calhode-red 
Common Anode -reJ 
Common Cathode-red 
Common Anode-red 
Common Anode-red t 1 
Common Anode-red 
Common Calhode-red i 1 
Common Cathode -red 
Common Cathode-red 
Common Cathode 
Common Cathode ± 1 
Common Cathode 
Common Cathode (FN 0500) 
Common Anode (FND510) 
Common Anode-red 
Common Anode -red 
Common Cathode red 
4 * 7 sgl. Digil-HHDP 
4x7Sgl Digft-LHOP 
Overrange character [ ± 1 ) 
4 x 7 Sol. Oipit-Hexadetimal 



RCA LINEAR 



CA3013T 
CA2023T 
CA3035T 
CA3039T 
CA3046N 
CA3059N 
CA3060N 
CA3080T 
CA30B1N 



2.15 CA3082N 

2.56 CA3083N 

2.48 CA3086N 

1.35 CA3089N 

1.30 CA3130T 

3.25 CA3140T 

3.25 CA3160T 

.65 CA3401N 

2.00 CA3600N 



CALCULATOR 


CLOCK C 


CHIPS/DRIVERS 


MM5309 


MM5725 




MM5311 


MM5738 






DM6B64 






















MM5369 






MM5387/1998A 


C.A LED driver 


1 SO 





8 pin LP 
14 pin LP 
16 pin LP 
18 pin LP 
20 pin LP 

14 pin ST 
16 pin ST 
18 pin ST 
24 pin ST 

8 pin SG 
14 pin SG 
16 pin SG 
18 pin SG 

I pin WW 
10 pin WW 

14 pin WW 
16 pin WW 

18 pin WW 



1-24 25-49 50-100 



IC SOLOERTAIL — LOW PROFILE (TIN) SOCKETS 



MC1408L7 

MC1408L8 

MC1439L 

MC3022P 

MC306IP 

MC4016I74416) 

MC4024P 

MC4O40P 

MC4044P 



$4.95 

575 
2.95 
2.95 
3.50 
7.50 



1-24 



22 pin LP S 37 

24 pin LP 38 

28 pin LP -45 

.27 36 pin LP 60 

a> SOLOERTAIL STAHDAHD (TIN) «P*"LP ra 
2B pin ST t .99 
36 pin ST 1.39 
40 pin ST 1.59 
SOLOERTAIL STANDARD (GOLD) 

2* pin SG S -70 



25-49 50-100 



28 pin SG 
36 pin SG 

40 pin SG 



1.65 



WIRE WRAP SOCKETS 
(GOLD) LEVEL #3 



22 pin WW $ 95 
24 pin WW 1 05 
28 pin WW 1.40 
36 pin WW 159 
40 pin WW 1 75 



1/4 WATT RESISTOR ASSORTMENTS - 5% 



10 OHM 
27 OHM 
63 OHM 



I? OHM 15 OHM 
J3 OHM 39 OHM 

8? OHM 100 OHM 



18 OHM 
47 OHM 
?0OHM 



22 OHM 
56 OHM 
50 OHM 



IBOOHM 220 OHM ,'70 OHM 330 OHM 390 OHM 
4 70 OHM 560 OHM 680 OHM 820 OHM 



220K 
560K 
I 5M 
3.9M 



100K 
270K 



120X 
330K 

8?0K 



ASST. BR Includes Resistor Assortments 1-7 (350 PCS.) 



SO PCS 


$1.75 


50 PCS 


1.75 


SO PCS 


1.75 


SO PCS 


1.75 


SO PCS 


1.75 


SO PCS 


1.75 


so pes 1.75 
$9.95 ea. 



$10.00 Min. Order - U.S. Fundi Only Spflc Sheets - 25t! 

Calif. Residents Add 6% Seles Tex 1979 Catalog Available - Send 4U stamp 

Postage -Add 5% piusSI Insurance lif desired I 

PHONE 

ORDERS 

WELCOME 

(415) 592-8097 

MAIL ORDER ELECTRONICS - WORLDWIDE 

1021 HOWARD AVENUE. SAN CARLOS. CA 94070 
ADVERTISED PRICES GOOD THRU SEPTEMBER 




AV-5-9100 

AV-5-9200 

AY-5-9500 

AY-5-237S 

HD0165 

74C922 



TELEPHONE/KEYBOARD CHIPS 

Push Button Telephone Dialler 

Repertory Dialler 

CMOS Clock Generator 

Keyboard encoder (86 keys) 

Keyboard Encoder (16 keys) 

Keyboard Encoder (16 keys) 



SU.95 
14.95 
4.95 
14.95 
7.95 
5.95 



ICM7045 
ICM7205 
ICM7207 
ICM7208 
ICM7209 



ICM CHIPS 

CMOS Precision Timer 
CMOS LED Stopwatch/Timer 
Oscillator Controller 
Seven Decade Counter 
Clock Generator 



24.95 
19.95 

7.50 
19.95 

6.95 



NMOS READ ONLY MEMORIES 

MCM6571 128 X9X 7 ASCII Shitted Willi Greek 13.50 

MCM6574 126 X 9 X 7 Math Symbol s Pictures 13.50 

MCM6575 128 X 9 X 7 Alphanumeric Control 13.50 

Character Generator 



MISCELLANEOUS 

TL074CN Quad Low Noise bi-let Op Amp 

TL494CN Switching Regulator 

TL496CP Single Switching Regulator 

11C90 Divide 10/11 Prescalnr 

95H90 Hi-Speed Divide 10/11 Prescaler 

4N33 Photo-Darlington Opto-lsolalor 

MK50240 Top Octave Freq. Generator 

OS0026CH 5Mhz 2-phase MOS clock driver 

111.308 .27" red num. display w/integ. logic chip 

MM5320 TV Camera Sync. Generator 

MM5330 4K Digit 0PM Logic Block ISpecisll 

LD110/111 3Vj Digit A/D Convener Set 



2.49 
4.49 
1.75 
19.95 
11.95 
3.95 
17.50 
3.75 
10.50 
14.95 
3.95 
25.00/set 



LITRONIX ISO-LIT 1 

Photo Transistor Oplo-lsolator 
(Same as MCT 2 or 4N25) 



2/990 



SN 76477 

SOUND GENERATOR 

Generates Complex Sounds 

Low Power - Programmable 

3.95 each 



TV GAME CHIP AND CRYSTAL 

AY-3-8500-1 and 2.01 MHZ Crystal (Chip & Crystal - nc . 

includes score display, 6 games and select angles, etc 7.95/SBl 



XR205 
XR210 
XR215 
XR320 
XR-L555 
XR555 
XR556 
XR567CP 
XR567CT 
XR1310P 1.30 
XR1468CN 3 85 
XR1488 1.39 
1.39 



S8 40 
4.40 
4.40 
1.S5 
1.50 



1.25 



EXAR 

JE2206KA 14.95 

JE2206KB 19.95 

XR1800 3.20 

XR2206 4.40 

XR2207 3.85 

XR2208 5.20 

XR2209 1.75 

XR2211 5.25 

XR2212 4.35 

XR2240 3.45 



XB2556 
XR2567 
XR3403 
XR4I36 
XR4151 
XR4194 
XR4202 
XR4212 
XR4558 
XR4739 
XR4741 



320 
299 
1.25 

1 25 

2 85 
4.93 
360 
2 05 

.75 
1.15 
1.47 



TYPE 
IN746 

1N7S1 

IN752 

IN753 

1N7S4 

IN757 

1N7S9 

1N9S9 

1N965 

1 NS232 

IN5234 

IN5235 

1N5236 

1N52*2 

IW5245 

1N456 

1N4S8 

1N485A 

1N4001 



DIODES 

VOLTS W 

3.3 400m 

5.1 400m 
66 4Q0m 

6.2 400m 
6.8 400m 
9.0 400m 

12.0 400m 

8.2 400m 

15 400m 

5.6 500m 

6.2 500m 

6.8 500m 

7.5 500m 

12 500m 

IS 500m 



PRICE 

4/1 00 
4/1.00 



180 10m 

50PIV 1 AMP 



6/1 00 

6/1.00 
5/1.00 
12/1.00 



TYPE 

1N4002 
1N4003 
1N4004 
1N40O5 
1N4006 
1N4007 
1N360O 
1N4148 
1N4154 
1N4305 
1N4734 
1N4735 
1N4736 
1H473B 
1N4742 
1N4744 
1N1183 
1N1184 
INI 165 
1N1186 
1N11B8 



VOLTS W 
100 PIV 1 AMP 

200 PIV 1 AMP 
400 PIV t AMP 
600 PIV 1 AMP 
800 PIV 1 AMP 
1000 PIV 1 AMP 
50 200m 
75 10m 
35 10m 



PRICE 

12/1.00 
12/1.00 
12/1 00 
10/1 00 
10/1.00 
10/1 00 
6/1.00 
15/1.1 



12 1w 
IS 1w 
50 PIV 35 AMP 

100 PIV 35 AMP 
150 PIV 35 AMP 
200 PIV 35 AMP 
400 PIV 35 AMP 



SCR AND FW BRIDGE RECTIFIERS 

C360 15A ru 400V SCH{2N1W9) 

C38M 3SA (a 600V SCfl 

2N2328 1.6A@ 300V SCR 

MOA 980-1 12A (rf 50V FW BRIDGE REC. 

MDA9B0-3 12AiTi 200V FW BRIDGE REC 



C106B1 

MPSA05 

MPSA06 

TIS97 

TIS98 

40409 

40410 

40673 

2N918 

2N2219A 

2N2221A 

2N2222A 

PN2222 Plastic 

2N2369 

2N2369A 

MPS2369 

2N24B4 

2N2906 

2N2907 

PN2907 PlasKc 

2N2925 

MJE2955 

2N3053 



.50 

.30 

5/1.00 

6/1 .DO 

6/1.00 



5/1.00 
7/1-00 
5.- 1 00 
4/1.00 
5/1.00 
4/1.00 
4/1.00 
5/1.00 
7/1 .00 
5/1.00 



Transistors 



2N3055 

MJE3055 

2N3392 

2N3398 

PN3567 

PN3568 

PN3569 

MPS3638A 

MPS3702 

2N3704 

MPS3704 

2N3705 

MPS3705 

2N3706 

MPS370S 

2N3707 

2N3711 

2N3724A 

2N3725A 

2N3772 

2N3823 

2N3903 



CAPACITOR 



5/1.00 
5/1.00 
3/1.00 
4/1.00 
4/1.00 
5/1.00 
5/1.00 
5/1.00 
5/1.00 
5/1.00 
5/1.00 
5/100 
5/1.00 
5/1 00 
5/1 00 
65 



^U30_ 



2N3904 
2N3905 

2N3906 
2N4013 
2N4123 
PN4249 
PN4250 
2N4400 
2N4401 
2N4402 
2N4403 
2N4409 
2N5086 
2N5087 
2N5088 
2N5089 
2N5129 
PN5134 
PN5138 
2NS139 
2N5210 
2N5449 
Si 



6/100 
4/1 00 
4/1.00 
4/1.00 
4/100 
4/1.00 
4/1 00 
5/1-00 
4/100 
4/1 00 
4/1.00 
4/1.00 



10 pi 
22 pi 
47 pf 

100 pi 
220 pi 
470 nl 

001ml 

.0022 

,0047ml 

,01ml 

.1/3SV 
15/35V 

.22/35V 
.33/35V 
.47/35V 
68/35V 
1.0/35V 



.47 /50V 

1.0/50V 

3 3/50V 

4.7/25V 

10/25V 

10/50V 

22/25V 

22/50V 

47/25V 

47/50V 

10O/25V 

100/50V 

220/25V 

220/50V 

470/25V 

1000/1 6V 

2200/16V 



50 VOIT CERAMIC 
DISC CAPACITORS 
_ iffiL 
.04 .03 OOVF 
04 .03 0O47 M F 
.04 03 OI^F 
.04 03 022^F 
.04 .03 047 >l F 
.04 .035 ,VF 
100 VOLT MYLAH FILM CAPACITORS 
.10 .07 ,022ml 
047ml 



CORNER 



.05 .04 .035 



12 .09 075 



.10 



.07 



■22ml ,33 2 
4-20% DIPPED TANTALUMS ISOLI01 CAPACITORS 

-28 .23 .17 1.5/35V .30 ,2 

.20 -23 .17 22/25V 31 2 

28 .23 .17 3.3/25V .31 .2 

.28 .23 .17 4.7/25V .32 ,21 

.28 .23 .17 6B/2SV .36 .3' 

I5/25V .63 .51 



.26 



.23 



.17 



MINIATURE ALUMINUM ELECTROLYTIC CAPACITORS 
W»l Ltwl H.dl.l L»d 

.15 .13 .10 47/25V .15 .13 

.16 .14 .11 .47/50V .16 .14 

.14 .12 .09 1.0/16V .15 .13 

• .15 .13 .10 1.0/25V .16 .14 

-15 .13 10 1.0/5OV .16 14 

16 .14 .12 4.7/16V .15 .13 

.17 .15 .12 4.7/25V 15 13 

.24 .20 .18 4.7/50V 16 14 

.19 .17 .15 10/16V .14 12 

.25 .21 ,19 10/25V 15 13 

.24 .20 .18 10/SQV 16 .14 

.35 .30 -28 47/50V .24 .21 

.32 .28 .25 10O/16V .19 .15 

.45 .41 .38 100/25V .24 .20 

33 .29 27 10O/50V 35 30 

.55 50 -45 220/16V ,23 .17 

.70 .62 .55 470/25V .31 .28 



232 BYTE September 1979 



Circle 200 on inquiry card. 



f Transistor Checker 




— Completely Assembled — 
— Battery Operated — 

The ASI Transistor Checker iscap- 
able of checking a wide range of 
transistor types, either "in circuit" 
or out of circuit. To operate, 
simply plug the transistor to be 
checked into the front panel 
socket, or connect it with the alli- 
gator clip test leads provided. 
The unit safely and automatically 
identifies low, medium and high- 
power PNP and NPN transistors. 
Size: 35t" x 6*/4" x 2" 
"C" cell battery not included. 



Trans-Check s 19.95 ea. 



Custom Cables & Jumpers 



Part No. 

DB25P-4-P 
DB25P-4-S 
DB25S-4-S 

DJ14-1 

DJ16-1 
DJ24-1 
DJ14-1-H 

DJ16-1-16 
DJ24-1-24 



DB 25 Series Cables 

Cable Length Connectors Price 

4 Ft. 2-DP25P S!5.95ea. 

4 Ft 1-OP25P/1-25S S16.95 ea. 

4 It. 2-DP25S $17.95 ea. 

Dip Jumpers 



1 1t 

i it. 

1 ft. 

1 it. 
1 1t 

i n 



1-14 Pin 
1-16 Pin 
1-24 Pin 
2-14 Pin 
2-16 Pin 
2-24 Pin 



$1.59 ea 
1.79 ea. 
2.79 ea 
2.79 ea. 
3.19 ea 
4.95 ea. 



For Cuitom Cablet ft Jumpers. 8m JAMECD 1979 Catalog lor Priclnp. 



CONNECTORS 

25 Pin-D Subminiature 

DB25P las pictured) PLUG (Meets RS232) S2.95 

DB25S SOCKET (Meets RS232) 13.50 

DB51226-I Cable Cover lor DB25P or DB25S $1.76 

PRINTED CIRCUIT EDGE-CARD 

ISfi Spaano-7in Double RaM-Out — Biluracieg Cooiscts — Fits 054 to 070 PC CaiOi 



15/30 

18/36 

22/44 

50/100 (.100 Spacing) 

50/100 (.125 Spacing) 



PINS (Solder Eyelet) 
PINS (Solder Eyelet) 
PINS (Solder Eyelet) 
PINS (Wire Wrap) 
PINS (Wire Wrap) 



S1.9S 
$2.49 
$2.95 
$6.95 
R681-1 $6.95 



4-Digit Clock Kit 




' Bright .357" ht. red display 

' Sequential flashing colon 

' 12 or 24 hour operation 

' Extruded aluminum case (black) 

' Pressure switches for hours, minutes & hold functions 

' includes all components, case and wall transformer 



i Size: 3V* : 



IV. x 1V« 



JE730 $14.95 



Jumbo 6-Digit Clock Kit 

» Four .630"ht. and two .3M"ht. 
common anode displays 

* Uses MM5314 clock chip 

* Switches for hours, minutes and hoi- 

* Hours easily viewable to 30 feet 

* Simulated walnut case 

* 115VAC operation 

* 12 or 24 hour operation 

* Includes all components, case and w 

* Size: 6V* x 3to x IV. 




JE747 $29.95 




. cath- 



ock chip 



nutes 



JE701 



• Bright .300 hi 
ode display 

• Uses MM5314 cl 

• Switche* lor hour 
and hold modes 

• Hrs. easily viewable to 20 ft. 

• Simulated walnut case 

• 115 VAC operation 

• 12 or 24 hr. operation 

• I net. all components, case & 
wall transformer 



• Size: 



< 3-1/8" 



IK" 



6-Digit Clock Kit $19.95 



REMOTE CONTROL 
TRANSMITTER ft RECEIVER 




$19.98 



Digital Stopwatch Kit 

* Use Intersil 7205 Chip 

* Plated thru double-sided P.C. Board 

* LED display (red) 

* Times to 59 mln. 59.59 sec. with auto reset 

* Quartz crystal controlled 

* Three stopwatches in one: single event, split 
nmulatlve] 4. taylor (sequential timing) 



L * 5lz< 



s 3 pern it f: batteries 
11 4.5" x 2.15" x .90" 



je900 $39.95 



MICROPROCESSOR COMPONENTS 



8212 
S214 

8216 
8224 
8228 

B223 
8238 
8251 
8253 
8258 
H257 
8259 




-BOIM/HMDA SUPPORT DEVICES- 
CPU 

8 -Bit InpuUOutpul 
Priority Interrupt Control 
Bi-Directional Eii.-s Drrvor 
Clock Generator/Driver 
Bus Driver 

System Controller/Bus Driver 
System Controller 
Proj. Comm. 1/0 (USAHT) 
Proo Interval Timer 
Prorj. Periph 1/0 (PPI) 
Prog. DMA Control 
Prog. Interrupt Control 
6800/6800 SUPPORT DEVICES — 
MPU 

MPU with Clock and FUm 
12BXB Static Ram 
Penph Inter Adapt (MC6B20) 
Prionty Interrupt Controller 
1024X8 Bit ROM (MC68A30-BI 
Asynchronous Comm. Adapter 
Synchronous Sena! Data Adapt. 
0-600 bps Digital MODEM 
2400 Ops Modulator 



-MICROPROCESSOR MANUALS- 



M-Z80 User Manual 

M-CDPtoO? User Manual 
M-2650 User Manual 



-ROM'S - 



2513(2140} Character Generaior(upper case) 

2513(3021) Character Generator^ lower case) 

2516 Character Generator 

MM5230N 2048-Bit Read Only Memory 



SH.95 
24.95 
5.95 
7.19 
12.95 
14.95 
7.95 
9.95 



Quad3-SU1eB 
MICROPROCESSOR CHIPS— MISCELLANEOUS - 

ZB0{78DC) CPU 
ZB0A(780-1) CPU 
CDP1802 CPU 
2650 MPU 

6502 



lil MPU w/clock, RAM. 1/0 lines 
PS0B5 CPU 

TMS9900JL 16-Bil MPU w /hardware, multiply 

4 divide 
SHIFT REGISTERS 



$19.95 
21.95 
19.95 
19.95 
11.95 
19.95 
1995 



1101 

1103 

2101(8101) 

2102 

21L02 

2I11(811t) 

2112 

2111 

2114L 

2114-3 

2114L-3 

5101 

5280/2107 

74B9 

74S200 

93121 

UPD111 

(MK1027) 
UP0416 

(MK1116) 
IMS4041- 

45NL 
TMS4045 
2117 



256X1 

1021X1 

255X4 

1024X1 

1024X1 

256X1 

256X4 

1024X4 

1024X4 

1024X4 

1024X4 

256X4 

4096X1 

16X4 

256X1 

256X1 

4K 



MM500H 

MM503H 

MM504H 

MM506H 

MM510H 

MM5016H 

2504T 

2518 

2522 

2524 

2525 

2527 

2528 

2529 

2532 

2533 

3341 

74LS670 



Dual 25 Bit Dynamic 
Dual 50 Bit Dynamic 
Dual 15 ili I Sialic 
Dual 100 Bit Static 
Dual 64 Bit Accumulator 
500*512 Bit Dynamic 
1024 Dynamic 
Hex 32 Bit Static 
Dual 132 Bit Static 
512 Static 
1024 Dynamic 
Dual 256 Bit Static 
Dual 250 Static 
Dual 240 Bit Susie 
Quad 60 Bit Slatie 
1024 Static 
Filo 



- RAMS 

Static 

Dynamic 

Static 

Static 

Static 

Static 

Static MOS 

Static 450ns 

Sialic 450ns law power 

Static 300ns 

Static 300ns low power 

Static 

Dynamic 

Static 

Static Trisiaie 

Static 

Dynamic 16 pin 

Dynamic 16 pin 

Sialic 

Static 

Dynamic 350ns 
(house marked) 
Dynamic 



14.95 
14.95 



1702A 

2716INTEL 

TMS2516 

<271B) 

TMS2532 

270B 

2716 T.I 



82S23 
B2S115 
B2S123 
741B6 



2048 



" PROMS 

FAMQS 
16K' EPROM 

I6K- EPROM 

'Requires single i-5V power supply 
4KX8 EPROM 

tin EPROM 

16K" EPROM 

'Requires 3 voltages. 



2048 
) 1024 
) 256 
32XB 
4096 
32X8 



A-Y-5-1013 30K BAUD 



EAM0S 

Tristale Bipolar 

Open C Bipolar 

Open Collector 

Bipolar 

Tristale 

TTL Open Collector 

TTL Open Collector 

Static 



12V 



$5.95 
59.95 
49.95 

89.95 
10.95 
29.95 



9.95 
3.95 
2.95 



CONTINENTAL SPECIALTIES 



Proto Board 203 




*75.00 



Modal 
Numbar 

PB-6 
PB-100 
PB-IOt 



LlWlH 

(Inchail Price 

6.0 « 4.5x1.4 S1S.95 

6.0x4.5x1.4 SU.95 

6.0x4.5x1.4 $22,95 



Proto Board 2034 




9124.95 



Modal LxWxH 

number llnclteil Pried 

PB-102 7.0x4.5x1.4 J251S" 

PD-1IB 9.0x6.0x1.4 $44.95 

PB-104 9.8x8.0x1.4 S54.95 



62-Key ASCII Encoder Keyboard Kit 




The JE610 62-Key ASCII Encoder Keyboard 
Kit can be interfaced into most any com- 
puter system. The JE610 Kit comes com- 
plete with an industrial grade keyboard 
switch assembly (62 keys), IC's, sockets, 
connector, electronic components and a 
double-sided printed wiring board. The 
keyboard assembly requires +5V @ 150mA 
and —12V @ 10mA for operation. 



& JE610 

FEATURES: 

•60 Keys generate the full 128 char- 
acters, upper and lower case ASCII 
set 

• Fully buffered 

• 2 user-define keys provided for 
custom applications 

• Caps lock for upper case only 
alpha characters 

•Utilizes a 2376 (40 pin) encoder 
read only memory chip 

• Outputs directly compatible with 
TTL/DTL or MOS logic arrays 

• Easy interfacing with a 16-pin dip 
or 18-pin edge connector 

JE610 $79.95 



JE200 



REGULATED POWER SUPPLY $& 




JE20Q $14.95 



5V-1 AMP 
POWER SUPPLY 

"Uses LM309K 

• Heat sink provided 
*PC Board construction 

• Provides a solid 1 amp 
@ 5 volts 

*Can supply up to ±5V. 

+ 9V and +12V with 

JE205 Adapter 
*l n eludes components, 

hardware & instructions 

• Size: 3 , /5"x5"x2"H 



JE205 



g 









ADAPTER BOARD 
-Adapts to JE200- 
±5V,±9Vand±12V 

■DC/DC converter w/ 

+ 5V input 
•Tortodal hi-speed 

switching XMFR 
'Short circ. protection 
■PC Brd. construction 
■Piggy-back to JE200 

board 
•Size:3 1 /$"x2"x9/16"h 

JE205 $12.95 



$10.00 Min. Order - U.S. Funds Only Spec Sheets - 254 

Calif. Residents Add 6% Sales Tax 1979 Catalog Available -Send 41 i stamp 

Postage — Add 5% plus $1 Insurance (if desired) 

PHONE 

ORDERS 

WELCOME 

(415) 592-8097 



FREE 

1979A 

CATALOG 



J ameco 



MAIL ORDER ELECTRONICS - WORLDWIDE 
1021 HOWARD AVENUE, SAN CARLOS, CA 94070 

ADVERTISED PRICES GOOD THRU SEPTEMBER 



The Incredible 
"Pennywhistle 103" 



$139.95 



Kit Only 




The PsnnywhliUi IDS is capable of recording data lo and from audio tape wilhoul 

critical speed requirements lor the recorder and il is able lo communicate directly with 

another modern and terminal lor telephone "hamming" and communications. In 

addition, it Is tree of aiiical adjust mentsand is bulit with non-precision, readily available 

pans. 

Diti Trentmlulon Method Frequency -Shift Keying, full-duplex (hall-duplei 

selectable). 

Miirmum Dili Rite 300 Baud. 

Dili Format Asynchronous Serial (return to mark level required 

between each character). 
Receive Channel Frequencies- . ..2025 Hi for space; 2225 Hi lor mark 
Trerwmlt Channel Frtquentlai ..Switch selectable Low (normal) = 1070 space, 

1270 mark; High = 025 space, 2225 mark. 

Receive Senilthrth; --46 dam accousiically coupled. 

Trinim.1L.ml -15 dbm nominal. Adjustable Irom -6 dbm 

lo-20 dbm. 
Receive Frequency Tolerance ...Frequency relerence automatically adjusts lo 

allow lor operation between 1800 Hz and 2400 Hr. 
Digital Data Interlace EIA RS-232C or 20 mA current loop (receiver is 

opto isolated and n on -polar). 

Power Requirement! 120 VAC, single phase. 10 Watts. 

FTiyalcal All components mounl on a single 5" by 9' 

printed circuit board. All components included. 
Requires a VOM. Audio Oscillator. Frequency Counter and/or Oscilloscope to align. 



TRS-80 
16K Conversion Kit 

Expand your 4K TRS-80 System to 16K. Kit 
comes complete with: 

■ 8 each UPD416-1 (16K Dynamic Rams) 250NS 
* Documentation for conversion 



TRS-16K 



$75.00 



COMPUTER CASSETTES 




.6 EACH 15 MINUTE HIGH 
QUALITY C-15 CASSETTES 

. PLASTIC CASE INCLUDED 
12 CASSETTE CAPACITY 

. ADDITIONAL CASSETTES 
AVAILABLE #C-15-$2.95 sa 

CAS-6 

$14.95 

(Case and 6 Cassettes) 



SUP 'R' MOD II 

UHF Channel 33 TV Interface Unit Kit 

Wide Band B/W or Color System 

* Converts TV to Video Display for 
home computers, CCTV camera, 
Apple II, works with Cromeco Daz- 
zler, SOL-20, IRS-80, Challenger, 
etc. 

MOD II is prettified to Channel 33 
(UHF}. 

* Includes coaxial cable and antenna 
transformer. 




MOD II 



$29.95 Kit 



Function Generator Kit 



• Provides 3 basic waveforms: 
sine, triangle & square wave 

• Frequency range Irom 1 Hz to 
100K Hz 

• Output amplitude from 0-volts to 
over 6 volts (peak lo peak) 

• Uses a 12V supply or a ±6V split 
supply 

• Incl. chip, P.C. board, compo- 
nents and insl ructions. 

JE2206B $19.95 




IDEAL FOR TRS 80 CASSETTE CONTROLLER 



"Plug/Jack interface to any 
computer system requiring 
remote control of cassette 
functions" 

The CC100 controls cassette 
motor functions, monitors 
tape location with its internal 
speaker and requires no 
power. Eliminates the plugging 
and unplugging of cables dur- 
ing computer loading opera- 
tion from cassette. 




#cc 

$29.50 




Micro- 
Miniature 
Joystick 



• 2 each 100K pots (Linear Taper) 

• Printed Circuit Board Mount 

• Size: 1"x 1-3/16"x 1-3/16" 

Micro-Miniature Joystick 



$4.95/ 



Circle 201 on inquiry card. 



BYTE Sepeember 1979 233 



Save $ on TRS-80 Products 



*\ TREMENDOUS 
> SAVINGS ON 
1?r TRS-80 SYSTEMS 



> 



Complete system includes: 
TRS-80 Level II, w/our48KRAM, Dual MPI 
Disk Drives, and the APPARAT DOS+ soft- 
ware ($2500 value), only $2049. Line printer 
and desk options available. 



SUPERDISK 

TF-7D Micropolis Largest capacity 
mini floppy, up to 1 95 Kbytes 
on 77 tracks with 77TK DOS+ $699 



Send for FREE 
Catalog 



A Complete Family 
Of Disk Drives 
To Choose 
From . . • 

In Stock 



TF-1 Pertec FD200, 5 1 A", 40 track use both sides $379 

TF-3 Shugart SA400, 5 1 A", 35 tracks same as tandy $389 

TF-5 MPI 5%" 40 track door lock and auto diskette $379 

ejection 

TDH-1 Pertec Dual Head mini-floppy 35 track same $499 

capacity as 2 drives 

All disk drive systems come complete with power supply and 
chassis 

• Two drive cable= $25 • Four drive cable= $35 




PRINTERS PRINTERS PRINTERS PRINTERS 



LP779 Centronics 779 
w/tractors 
LP700 Centronics 700 
LP701 Centronics 701 
NEC Spinwriter 



$1099 

$1175 
$1759 
$2499 



CENTRON 




LP702 Centronics 702 $1899 

LP703 Centronics $2540 

LP1 Centronics P1 $ 399 

Centronics cables $ 39 



Add-on Disk Drives 

DOES NOT INCLUDE POWER SUPPLY OR CHASSIS 



• Pertec FD200 or MPI B-52 

• Shugart SA400 (unused) 

• Pertec Dual Head 



$272.00 
$282.00 
$399.00 



NEW PRODUCTS 

• Small System RS232 Interface $ 49.00 

• Expansion Interface w/32K $499.00 

• AC Line Interference Eliminator $ 18.95 

• AC Isolator (6 connectors) $ 45.95 

• Telephone Interface $179.95 

• Verbatum 5" soft sector Diskettes $ 3.39 



IMPROVE TRS-80 

PERFORMANCE WITH 

NEWDOS+ 

Over 200 modifications, 
corrections and enhance- 
ments to TRS DOS. 
Includes utilities. Available in 
two versions: 
35 Track version $99 
40 Track version $110 




All prices cash discounted. 
Freight FOB/Factory 



Memory 

16KM 16KRAM Kit 
Computer $74 
Expansion Interface $78 



«T 



/MCROCO/VIPUrER 

TECHNOLOGY 
INCORPORATED 



2080 South Grand Ave. 

Santa Ana, CA 92705 

(714) 979-9923 



Circle 277 on inquiry card. 




Software 

• Accounts Receivable $39 

• Inventory Control $39 

• Job Entry/Status $75 

• General Ledger $79 

• Game Diskette $19 

• AJA Word Processor $75 



6000 E. Evans Ave., Bldg. 2 
Denver, CO 80222 
(303) 758-7275 



p pa rat, Inc. 



Circle 15 on inquiry card. 



CaUFornia DiqiTAl 

Post Office Box 3097 B • Torrance, California 90503 



Sankyo Magnetic 
Card Reader 



These Sankyo I/O units are capable of storing and retrieving over 

400 characters of data in under two secords. 

The flexibility of this device lends itself t'o numerous applications. 
]IAs an input reader to a computerized security system, the com- 
Ijputer has the ability of identifying the card holder and admitting 
1 only those individuals who are authorized to enter the premises 
[■during specified time frames. The device is also suitable for 
[maintaining customer information files, or any other application 

where small amounts of information must be quickly entered into 

a data processing system. 

Accepts 2" by 4" HP style mag-cards. (Similar to bank cards. ) 

Motorized feeder pulls the magnetic card across the four channel 
j read/write head. NEW surplus, original cost $200. Full documentation 



CONNECTORS 



your choice 



f— i HOCO | DB2SP 

r~" ^ mile plus It hooi 

I ■ ' _ j DB25S female 

MUUUUMJL 3.95 



iuuuuiu. 

H j ? 



o<- 



Qty. ft. male hd. 
10 Hi 2.45 1.15 
25 115 2.25 1.05 
100 2.15 1.90 .15 
WO 2.251.00 JS 
IK 1.07 1.37 .73 



Edge 
Cannae tors 




fatal HMff .1251.250 

Iks.I v/w.l2Sctattrs 
Altilr lold.rl. II. 140,o. 

specials 

22/44 Klai lJ.Ht.15t" 
25/50 aaMartia .150" 

38/72 wldap.lt W/W.155 



GOLD 

100 PIN 

IMSAI/ALTAIR 

• 3.05 3/1 I 00 
•4.05 3/(13.00 
•5.M 3/(15.00 

(1.55 3/15.00 
il.09 3/(2.00 

• 1.15 3/(5.00 



S-100 Mother Board 
Quiet 




HEXADECIMAL KEYBOARD 

MaxISwitch hexadecimal kayboawds tin designed for <4 * J,4j 85 

microcomputer syslema that r«qulr«4-blt output «;'i/ •■■■^T* 

In eUuidard hex coda. 

Each assembly constats of 18 hermeti- 

caily sua led road switches and TTL " 

shot" debounco circuitry. 

Reliable low friction acatal raaln 

plungers a/a cradltad (or the amooth 

operation and long Ufa of this premium 

keyboard. 

Rsqulraa single + 5 volt aupply. 





'24.88 



^s ^UNIVAC 
KEYBOARD 

Tht limoui Spoirry Univac 1710 Holianiti keyboard aiaambty 
15 now i.niBbK Irom California Industrial for only $24 f!3 
The iQoii compular input drrica 'or accountants and 
mathernilicunjj The mimetic keyi art placad On Ih* lower 
thiao rowi Id rttcmbl* ■ fen Hay adding mac nine This 
lor mil allows one handed numeric date entry. 

Complete with ' 



TEN 

_IPX 

50 



**A% Cxn^nh 9 Certified Digital 
4^L SCDtCTl CASSETTES 

*' 3?5 ""* ND Wort drop. BIT! 



wTs 



TELETYPE MODEL 4 3 



Ev.ti If w. biva t. g Ivt tk.M 
.way, w.t. gal.f to ship mora 
43'i la 1979 than t>a anragata 
tf til oar compalltors. 



Model 43AAA 

«CH _JL 



*925. 875. 



TTL) 

85a 




825. 



R5-232 Interface"*." nd»7S0O ..fjpf.i ' Wt M 



FREE 



PLASTIC LIBRARY CASE 

with purchase of each box of .... 
' itlm mInl-dlskeWei. 55 value. 




BOX of 10 



IMOduLATOR 



Trio Atari R.F. Modulator 
allows computer data to be 
dla played directly upon your 
Istlng television system, 
| Thla unit converts the sig- 
nal Irom the Apple II and 
other video sources Into 
television frequencies. 
Operates Irom single 5 
vol I supply. Complete 
^Jit»e_^*"* ^- «H h metal case, mating 
VrjjV*'^^— —""^ R.F. connector and 15 
feet ol coax cable. Schematics 
and Instructions Included. 




KETTES 



SPGCiflL 



APPLE (I 

IBK MEM OR 

COLOR • GRAPHICS* SOUND 

$1024 



PLUS SH1PPIHC 



Mff.aui. 
Retail.... 

•1195 



Diskettes 

| 8lnchSoft(IMH 
8 inch 32 sector 
Mini Soft sec. 
Mini 10 sector 
Mini 16 sector 




hugart Associates 



SA800-R Floppy Disk Drive 

The most cost effective way to store data proc- 
essing information, when random recall is a 
prime factor. The SA800 is fully compatible 
with the IBM 3740 format. Write protect cir- 
cuitry, low maintenance & Shugart quality. 



>44950 



KEYBOARD 

ASCII ENCODED 




KEYTRONIC 
ASCII & ASCII 
complement. 
♦Ten key data pad 1 
♦ Cursor controls 
♦Six user switches| 

* Alpha L ock 
*Auto repeat 
♦Single 5 volt. 

♦ Glass reed. 

NEW 




TRS-80$| 
I APPLE II 

16k memory (8) 4116's 



• As you may be aware, publishers 
require advertisers to submit their 
ad copy 60 to 90 days prior to "press" 
date. That much lead time in a volatile market place, 
such as memory circuits, makes it extremely difficult 
to project future cost and availability. 
To obtain the best pricing on memory we have made 
volume commitments to our suppliers, which in turn 
affords us the opportunity to sell these circuits at the 
most competitive prices. Please contact us if you 
if you have a demand for volume state of the art mem- 
ory products. 



STATIC 

21L02 450nS. 
21L02 250nS. 
2114 lKt4 450 
2114 lKf.4 300 
4044 4Kxl 450 

4044 4Ktl 250 

4045 1Kx4 450 
4045 1Kc4 250 
5257 low pow. 



1-31 32-99 100-5C -999 1K+ 

1.19 .99 .95 .90 .85 

1.49 1.39 1.25 * * 

5.95 5.50 5.25 4.75 4.50 

8.95 8.50 8.00 * * 

5.95 5.50 5.25 * * 

9.95 9.50 9.00 * * 

8.95 8.50 B. 00 * * 

9.95 9.50 9.00 * * 

5.95 5.50 5.00 4.80 4.60 



SPECIAL CIRCUITS 



Z80A 4 MHz. 

8080A CPU 

8085 

8086 Intel 16 bits 

TMS9900 16 bits 



24.95 

9.95 

22.50 



AY5-1013A UART 4.95 
Floppy Disc Controllers 
WD 1771 single D. 39. 95 
WD 1781 Double D 65. 00 
WD 1791 D/D3740 * 



64+ 
4.00 
9.00 



E PROMS 1-15 16-63 

1702A 2K 4.95 4.50 

2708 8K 9.95 9.50 

2716 5vl6K 39.95 35.00 

2716 TI 24.88 20.00 

2532 * * 



^ !E3 



PORTABLE DATA ENTRY SYSTEM 



These used data terminals were originally designed for chain store inventory con- 
trol and order entry systems. The operator enters the inventory control number, 
merchandise on hand and the unit price. After all pertinent data has been entered into 
the recorder, the main warehouse is telephoned, the handset is placed in the acoustic 
coupler and all the recorded information is transmitted back to the master computer. 
With a little Imagination and one of these portable entry systems, you should be able 
to exchange programs and computer information with associates across the country. 
Ail units were removed from service in working condition. Original cost $2,500. 
Each system comes complete with: 

•Portable Cassette Drive Unit -Five Gould "D" NiCads "DB25 Cable 

■Removable Entry Keyboard ■Acoustical Coupler ..Shoulder starp 

with LED Display "Battery Charger "Full Documentation 



*-98 188 .81.73.68 | 

SPDT Miniature Toggles 

7101 CM 0N-N0NC-0N 
7107 jbt ONOFF(mnt.ON) I 
7101 CK ON(momint.ON) 

Rocker JBT DPDT 

Rotary 3P-4Poi. 

Rotary 3P-6-Pos. 

Pnih B (NO.) $ 39ei. 4/S1 



DIP Switch 




DISCOUNT 




HSTI1 WO 



UUire Wrap Center 



It'a not offen that California Digital ven- 
tures into the distribution of consumer pro- 
ducts, but we have reaently come accrose 
a product that appears so unique that we just had to add it 
to our product line. This is the System X-10 manufactured 
by the B SR turntable company. This apace age system will re- 
motely control any light or appliance in your home or office. Command sig- 
nals are transmitted from the command console over your existing wiring. 
From your bed or easy chair you can control up to 16 different electrical de- 
vices inside and outside your home. Use the System X-10 to control your 
stereo, television or any light fixture on the premises. 

The basic sampler package comes complete with command console, battery 
operated ultrasonic controller, one each of the appliance module, lamp mod- 
ule and wall switch. The basic package is priced at only $99.50 Additional 
modules are available for $13. 95 each. f 



IC SOCKETS 



wlr. wrap 
». 25 SO 


low profile 

i«. 25 SO 




17< 16 IS 




37<36 35 


IS 17 16 


31 37 34 


19 IS 17 


99 93 IS 


36 35 34 


169 1SS 119 


63 60 58 



£.t KYNARwiSr 

.98 900 1,000 11,000 

*9. SIS. (105. 



SS9.95 -f 

BW630 ' 



(213)679-9001 



19 nil inquiry i aid 



COMPUCRUISE 

Put a computer in 
your car, which gives 
you the most effec- 
tive and functional 
cruise control ever 
designed, plus com- 
plete trip computing, 
fuel management sys- 
tems, and a remark- 
able accurate quartz 
crystal time system. 
So simple a child can 
operate, the new 
CompuCruise com- 
bines latest computer 
technology with 
state-of-the-art re- 
liability in a package 
which will not likely be 
available on new cars 
for years to come • 
Cruise Control 'Time, 
E.T., Lap Timer, Alarm 

• Time, Distance, Fuel 
to Arrival • Time, Dis- 
tance, Fuel to Empty • 
Time, Distance and 
Fuel on Trip • Current 
or Average MPG, 
GPH»Fuel Used, Dis- 
tance since Fi Hup • 
Current and Aver- 
age-Vehicle Speed • 
Inside, Outside or 
Coolant Temperature 

• Battery Voltage • 
English or Metric 
Display. $199.95 



1 HIDSCEIU 
I Hi'..u'ii-:,ui 






L^* 


f* tBs^cns 



FLOPPY DISK 
STORAGE BINDER 

This black vinyl 
three-ring binder 
comes with ten 
transparent plastic 
sleeves which ac- 
commodate either 
twenty, five-inch or 
ten, eight-inch floppy 
disks. The' plastic 
sleeves may be or- 
dered separately and 
added as needed. A 
contents file is in- 
cluded with each 
sleeve for easy iden- 
tification and organiz- 
ing, Binder & 10 hol- 
ders $14.95 Part No. 
BBOO; Extra holders 
95* each. Part No. 
BOD 




OPTO-ISOLATED 

PARALLEL INPUT 

BOARD FOR 

APPLE II 

There are 8 in- 
puts that can be dri- 
ven from TTL logic or 
any 5 volt source. The 
circuit board can be 
plugged into any of 
the 8 sockets of your 
Apple II. It has a 16 pin 
socket for standard 
dip ribbon cable con- 
nection. 

Board only $15.00. 
Part No. 120, with 
parts $69.95. Part 
Np. 120A. 




TIDMA 

• Tape Interface Direct 
Memory Access • Re- 
cord and play programs 
without bootstrap load- 
er (no prom) has FSK 
encoder/decoder for 
direct connections to 
low cost recorder at 
1200 baud rate, and 
direct connections for 
inputs and outputs to 
a digital recorder at 
any baud rate »S-100 
bus compatible • Board 
only $35.00 Part No. 
112, with parts $110 
Part No. 1 1 2A 




SYSTEM 
MONITOR 

80B0, 8085, or Z-BD 
System monitor for use 
with the TIDMA board. 
There is no need for the 
front panel. Complete 
with documentation 
$12,95. 



16K EPROM 

Uses 2708 EPROMS, 
memory speed selec- 
tion provided, ad- 
dressable anywhere in 
65K of memory, can 
be shadowed in 4K in- 
crements. Board only 
$24.95 part no. 
7902, with parts less 
EPROMs $49.95 part 
no. 7902A. 




ASCII KEYBOARD 

TTL & DTL compatible • Full 67 key array 

• Full 128 character ASCII output • Positive 
logic with outputs resting low • Data Strobe 

• Five user-definable spare keys • Standard 
22 pin dual card edge connector • Requires 
+5VDC, 325 mA. Assembled S. Tested. 
Cherry Pro Part No. P70-05AB. $135.00. 




ASCII KEYBOARD 

53 Keys popular ASR-33 format • Rugged 
G-10 P. C. Board • Tri-mode MOS encoding 
• Two-Key Rollover • MOS/DTL/TTL Compat- 
ible • Upper Case lockout • Data and Strobe 
inversion option • Three User Definable 
Keys • Low contact bounce • Selectable Par- 
ity • Custom Keycaps • George Risk Model 
753. Requires +5, -12 volts. $59.95 Kit. 



ASCII TO CORRESPONDENCE 
CODE CONVERTER 

This bidirectional board is a direct replace- 
ment for the board inside the Trendata 1000 
terminal. The on board connector provides 
RS-232 serial in and out. Sold only as an 
assembled and tested unit for $229.95. 
Part No. TA 1000C 



DISK JACKET™ 

Made from heavy duty 
.0095 matte plastic 
with reinforced 

grommets. The mini- 
diskette version holds 
two 5-1/4 inch disk- 
ettes and will fit any 
standard three ring 
binder. The pockets to 
the left of the disk- 
ette can be used for 
listing the contents of 
the disk. Please order 
only in multitudes of 
ten. $9.95/10 Pack. 




INTERNATIONAL 

MICROPROCESSOR 

DICTIONARY 

English, French, Dan- 
ish, German, Italian, 
Hungarian, Norwe- 
gian, Polish, Spanish, 
Swedish. 10 lan- 
guages, 28 pp. 
SYBEX. Ref. IMD. 
$4.95 



VIDEO TERMINAL 

16 lines, 64 columns • 
Upper and lower case • 
5x7 dot matrix • 
RS-232 in -RS-232 
out with TTL parallel 
keyboard input • On 
board baud rate 
generator 75, 110, 
150, 300. 600, & 
1200 jumper selecta- 
ble • Memory 1024 
characters (7-21 L02) 
• Video processor chip 
SFF96364 by Necu- 
lonic • Control char- 
acters CCR, LF, -., *-, 
t, f , non destructive 
cursor, CS, home, CL • 
White characters on 
black background or 
vice-versa • With the 
addition of a keyboard, 
video monitor or TV 
set with TV interface 
(part no. 107A) and 
power supply this is a 
complete stand alone 
terminal 'also S-100 
compatible • requires 
+16, S. -16 VDC at 
100mA, and 8VDC at 
1A. Part no. 1000A 
$199.95 kit. 




RS-232/20mA 
INTERFACE 

This board has two 
passive, opto-isola- 
ted circuits. One con- 
verts RS-232 to 
20mA, the other con- 
verts 20mA to RS- 
232. All connections 
go to a 10 pin edge 
connector. Requires 
+12 and -12 volts. 
Board only $9.95, 
part no. 7901, with 
parts $14.95 Part 
No. 7901A. 




COMPUCOLORII 

Model 3, 8K $1395. 
Model 4, 16K$1595. 
Model 5, 32K $1895. 
Prices include color 
monitor, computer, 
and one disk drive. 



mm g *— *- 



PET COMPUTER 

With 32K & monitor - 
$1195. Dual Disk 
Drive -$1195. 




ffccippta 



APPLE II PLUS 

16K - $995, 32K 
$1059, 48K -$1123. 
Disk&cont $589 




6502 

APPLICATIONS 

BOOK 

Z80 APPLICATIONS 

BOOK* 
This book will teach 
you how to connect a 
board to the outside 
world and implement 
practical applications 
for the 6502, (or 
280). Applications 
range from home con- 
trol (a complete alarm 
system, including 
heat sensor), to in- 
dustrial applications. 
You will learn tech- 
niques ranging from 
simulated traffic con- 
trol to analog-digital 
conversion. All exper- 
iments can be realized 
with a minimum of ex- 
ternal (low-cost! 
components. They are 
directly applicable to 
any 6502-based 
board such as SYM, 
KIM, AIM 65. This 
book also studies in 
detail input-output 
techniques and com- 
ponents, and is the 
I logical continuation of 
C202 tor C2B0). By 
Rodney Zaks. 

SYBEX. 6502: Ref. 
D302; Z80: Ref 
D380. Each $12.95 



T.V. INTERFACE 

• Converts video, to, 
AM modulated RF, 
Channels 2 or 3. So 
powerful almost no 
tuning is required. On 
board regulated power 
supply makes this ex- 
tremely stable. Rated 
very highly in Doctor 
Dobbs' Journal. Recom- 
mended by Apple • 
Power required is 12 
volts AC C.T., or +5 
volts DC • Board only 
$7.60 part No. 107, 
with parts $1 3.50 Part 
No. 107A 





PARALLEL TRIAC 

OUTPUT BOARD 

FOR APPLE II 



This board has B tnacs capable of 
switching 110 volt 6 amp loads (660 watts 
per channel) or a total of 5280 watts. Board 
only $15.00 Part No. 210, with parts 
$119.95 Part No. 21 OA. 



TX fVfJpr • Mention part no. description, and price. In USA shipping paid by us for orders accompanied by check or money order. 
' We accept C.O.D. orders in the U. S. only, or a VISA or Master Charge no., expiration date, signature, phone no., 
shipping charges will be added. CA residents add 6.5% for tax. Outside USA add 10% for air mail postage and han- 
dling. Payment must be in U. S. dollars. Dealer inquiries invited. 24 hour order line (408) 226-4064. 



Send for FREE Catalog ... a big self-addressed envelope with 41 'postage gets it fastest! 



ELECTRONIC SYSTEMS De P l - B p - ° Box 21638,SanJose, CAUSA 95151 



236 BYTE September 1979 



Circle 125 on inquiry card. 



TRS-80 ES 
SERIAL I/O 

• Can input into basic 

• Can use LLIST and 
LPRINT to output, or 
output continuously • 
RS-232 compatible • 
Can be used with or 
without the expansion 
bus • On board switch 
selectable baud rates 
of 110, 150,300,600, 
1 900, 9400, parity or 
no parity odd or even, 
5 to 8 data bits, and 1 
or 2 stop bits. D.T.R. 
line • Requires +5, 
-12 VDC • Board only 
$1 9.95 Part No. 8010, 
with parts S59.95 Part 
No. 801 OA. assembled 
$79.95 Part No. 8010 
C. No connectors pro- 
vided, see below. 




EIA/RS-232 con- 
nector Part No 
OB25PS600.«ith 
9'. 8 conductor 
cable S1095 Part 
No DB25P9 



nobon cable 
witbattached con- 
nectors to fit TRS- 
80 end our serial 
board S1 9.95 Part 
No. 3CAB40. 



RS-232/ TTL 
INTERFACE 

• Converts TTL to RS- 
232, and converts RS- 
232 to TTL* Two sep- 
arate circuits • Re- 
quires -12 and +12 
volts • All connections 
go to a 10 pin gold 
plated edge connector 

• Board only S4.50 
Part No. 232, with 
parts $7.00 Part No. 
232A 10 Pin edge 
connector $3.00 Part 
No. 10P 




MODEM 

• Type 1 03 • Full or 
half duplex • Works up 
to 300 baud • Origi- 
nate or Answer • No 
coils, only low cost 
components • TTL in- 
put and output-serial 

• Connect 8 fi speak- 
er and crystal mic. 
directly to board • 
Uses XR FSK demod- 
ulator • Requires +5 
valts • Board only 
$7.60 Part No. 109. 
with parts $27.50 Part 
No. 109A 




DISKETTES 




Box of 10, 5" $29.95, 
8" $39.95. 
Plastic box, holds 10 
diskettes, 5" - $4.50, 
8" -$6.50. 



RS-232/TTY 
INTERFACE 

This board has two 
active circuits, one 
converts RS-232 to 
20mA, and the other 
converts 20mA to 
RS-232. Requires 
+12 and -12 volts. 
Board only $4.50 Part 
No. 600. with parts 
$7.00 Part No. 600A. 




S-100 BUS 
ACTIVE TERMINATOR 

Board only $14.95 Part No. 900, with parts 
$24.95 Part No. 900A 



.■: : -,V,,' !: .. 




APPLE IK- 
SERIAL I/O 
INTERFACE 



Baud rate is continuously adjustable from 
to 30,000 • Plugs into any peripheral 
connector • Low current drain. RS-232 input 
and output • On board switch selectable 5 to 
B data bits, 1 or 2 stop bits, and parity or no 
parity either odd or even • Jumper selectable 
address • SOFTWARE • Input and Output 
routine from monitor or BASIC to teletype or 
other serial printer • Program for using an 
Apple II for a video or an intelligent terminal. 
Also can output in correspondence code to 
interface with some selectrics. • Also 
watches DTR • Board only $15.00 Part No. 
2, with parts $42.00 Part No. 2 A, assembled 
$62.00 Part No. 2C 



8K EPROM piiceon 

Saves programs on PROM permanentlytuntil 
erased via UV light] up to 8K bytes. Programs 
may be directly run from the program saver 
such as fixed routines or assemblers. • S- 
100 bus compatible • Room for BK bytes of 
EPROM non-volatile memory (2708's). • On- 
board PROM programming • Address 
relocation of each 4K of memory to any 4K 
boundary within 64K • Power on jump and 
reset jump option for "turnkey" systems and 
computers without a front panel • Program 
saver software available • Solder mask both 
sides • Full silkscreen for easy assembly. 
Program saver software in 1 2708 EPROM 
$25. Bare board $35 including custom coil, 
board with parts but no EPROMS $1 39, with 
4 EPROMS $179, with 8 EPROMS $219. 




WAMECO PRODUCTS 

WITH 

ELECTRONIC SYSTEMS PARTS 

FDC-1 FLOPPY CONTROLLER BOARD will 
drive shugart, pertek, remex 5" SB" drives 



up to 8 drives, on board PROM with power 
boot up, will operate with CPM (not 
included). PCBD $42.95 



FPB-1 Front Panel. (Finally) IMSAI size hex 
displays. Byte or instruction single step. 
PCBD $42.95 

MEM-1A 8KxB fully buffered, S-100, uses 
2102 type RAMS. 
PCBD $24.95, $1 68 Kit 

QMB-12 MOTHER BOARD, 1 3 slot, termi- 
nated. S-1 00 board only $34.95 

$89.95 Kit 

CPU-1 8080A Processor board S-1 00 with 

8 level vector interrupt PCBD . . $25.95 

$89.95 Kit 

RTC-1 Realtime clock board. Two independ- 
ent interrupts. Software programmable. 
PCBD $25.95, $60.95 Kit 

EPM-1 1702A4K EPROM 

card PCBD $25.95 

$49.95 with parts less EPROMS 

EPM-2 2708/2716 16K/32K 

EPROM card PCBD $24.95 

$49.95 with parts less EPROMS 

QMB-9 MOTHER BOARD. Short Version of 

QMB-1 2. 9 Slots PCBD $30.95 

$67.95 Kit 

MEM-2 16Kx8 Fully Buffered 2114 Board 
PCBD $25.95, $269.95 Kit 



T.V. 
TYPEWRITER 

• Stand alone TVT 

• 32 char/line, 16 
lines, modifications for 
64 char/line included 

• Parallel ASCII (TTL) 
input • Video output 

• 1 K on board memory 

• Output for computer 
controlled curser • 
Auto scroll • Non- 
destructive curser • 
Curser inputs: up, down, 
left, right, home, EOL, 
EDS • Scroll up, down 

• Requires +5 volts 
at 1.5 amps, and -12 
volts at 30 mA • All 
7400, TTL chips • 
Char. gen. 2513 • 
Upper case only • 
Board only $39.00 
Part No. 106, with 
parts $145.00 Part 
No. 1 06A 




UART& 
BAUD RATE 
GENERATOR 

• Converts serial to 
parallel and parallel to 
serial • Low cost on 
board baud rate gener- 
ator • Baud rates: 
110, 150, 300, 600, 
1200, and 2400 • 
Low power drain +5 
volts and -12 volts 
required • TTL com- 
patible • All characters 
contain a start bit, 5 
to 8 data bits, 1 or 2 
stop bits, and either 
odd or even parity. • All 
connections go to a 44 
pin gold plated edge 
connector • Board only 
$12.00 Part No. 101, 
with parts $35.00 Part 
No. 101 A, 44 pin edge 
connector $4.00 Part 
No. 44P 



TAPE 
INTERFACE 

• Play and record Kan- 
sas City Standard tapes 

• Converts a low cost 
tape recorder to a 
digital recorder • Works 
up to 1200 baud* Dig- 
ital in and DUt are TTL- 
serial • Output of 
board connects to mic. 
in of recorder • Ear- 
phone of recorder con- 
nects to input on board 

• No coils • Requires 
+5 volts, low power 
drain • Board only 
$7.60 Part No. 111, 
with parts $27.50 Part 
No. 111A 




HEX ENCODED 
KEYBOARD 

E.S. 
This HEX keyboard 
has 1 9 keys, 1 6 encod- 
ed with 3 user defin- 
able. The encoded TTL 
outputs, 8-4-2-1 and 
STROBE are debounced 
and available in true 
and complement form. 
Four onboard LEDs 
indicate the HEX code 
generated for each 
key depression. The 
board requires a single 
+5 volt supply. Board 
only $15.00 Part No. 
HEX-3, with parts 
$49.95 Part No. HEX- 
3A. 44 pin edge con- 
nector $4.00 Part No. 
44P. 





DC POWER SUPPLY 



• Board supplies a regulated +5 
volts at 3 amps., +1 2, -1 2, and -5 
volts at 1 amp. • Power required is 
8 volts AC at 3 amps., and 24 volts 
AC C.T. at 1.5 amps. • Board only 
$12.50 Part No. 6085, with parts 
excluding transformers $42.50 
Part No. 60B5A 




TO Ofdfir ■ Mention P art no - description, and price. In USA shipping paid by us for orders accompanied by check or money order. 
1 We accept C.O.D. orders in the U. S. only, or a VISA or Master Charge no., expiration date, signature, phone no., 
shipping charges will be added. CA residents add 6.5% for tax. Outside USA add 10% for air mail postage and han- 
dling. Payment must be in U. S. dollars. Dealer inquiries invited. 24 hour order line (408) 22B-40B4. 



Send for FREE Catalog ... a big self-addressed envelope with 41* postage gets it fastest! 



ELECTRONIC SYSTEMS De Pt- B . p - °- Box 21638,SanJose, CAUSA 95151 



Circle 125 on inquiry card. 



BYTE September 1979 237 



Circle 126 on inquiry card. 



The.) VTA-FRANS 1000 



A completely refurbished 
IBM Selectric Terminal with 
built-in ASCII Interface. 



Features: 



$1395 



300 Baud 

14.9 characters per second 

printout 

Reliable heavy duty Selectric 

mechanism 

RS-232C Interface 

Documentation included 

60 day warranty -parts and 

labor 

High quality Selectric printing 

Off-line use as typewriter 

Optional tractor feed available 

15 inch carriage width 



HO WTO ORDER 
DATA-TRANS 1000 

1. We accept Visa, Master 
Charge. Make cashiers checks or 
personal check payable to: 

DATA-TRANS 

2. All orders are shipped 
F.O.B. San Jose, CA 

3. Deliveries are immediate 




For orders and information 

DATA-TRANS 

2154 0TooleSt 

UnitE 

San Jose, CA 95131 

Phone: (408) 263-9246 



MICRO- 
PROCESSORS: 
FROM CHIPS TO 
SYSTEMS 

This book cover all as- 
pects of microp- 
rocessors, from the 
basic concepts to ad- 
vanced interfacing 
techniques, in a pro- 
gressive presenta- 
tion. It is independent 
from any manufac- 
turer, and presents 
uniform standard 
principles and design 
techniques, including 
the interconnect of a 
standard system, as 
well as specific com- 
ponents. It intro- 
duces the MPU, how 
it works internally, the 
system components 
(ROM, RAM, UART, 
PIO, others), the sys- 
tem interconnect, 
applications. pro- 
gramming, and the 
problems and tech- 
niques of system de- 
velopment. By R. 
Zaks. SYBEX. Ref. 
C201.S9.95 



MICRO- 
PROCESSOR 
INTERFACING 
TECHNIQUES 

Microprocessor in- 
terfacing is no longer 
an art. It is a set of 
techniques, and in 
some cases Just a set 
of components. This 
comprehensive book 
introduces the basic 
interfacing concepts 
and techniques, then 
presents in detail the 
implementation de- 
tails, from' hardware 
to software. It covers 
all the essential per- 
ipherals, from key- 
board to floppy disk, 
as well as the stan- 
dard buses (S100 to 
IEEE 4BB) and intro- 
duces the basic trou- 
bleshooting tech- 
niques. (2nd Ex- 
panded Edition). By 
Austin Lesea and R. 
Zaks. Ref. C207 
SYBEX. $11.95 



PROGRAMMING 
THE 6502 

PROGRAMMING 
THEZBO 

PROGRAMMING 
THE 8080' 
It covers all essential 
aspects of program- 
ming, as well as the 
advantages and dis- 
advantages of the 
6502 and should 
bring the reader to 
the point where he 
can start writing 
complete applications 
programs. For the 
reader who wishes 
more, a companion 
volume is available: 
The 6502 Applica- 
tions Book. By R. 
Zaks. 6502: Ref. 
C202; Z80: Ref. 
C280; B080: Ref. 
C208. SYBEX. Each 
$10.95 




44 BUS MOTHER 
BOARD 

Has provisions for tan 
44 pin (.156) connec- 
tors, spaced 3/4 of an 
inch apart. Pin 20 is 
connected to X, and 
22 is connected to Z 
for power and ground. 
All the other pins are 
connected in parallel. 
This board also has 
provisions for bypass 
capacitors. Board 
cost $15.00 Part No. 
102. Connectors 

$3.00 each Part No. 
44WP. 




AN INTRODUCTION 

TO PERSONAL AND 

BUSINESS 

COMPUTING 

No computer back- 
ground is required. 
The book is designed 
to educate the reader 
in all the aspects of a 
system, from the se- 
lection of the mic- 
rocomputer to the 
required peripherals. 
By Rodnay Zaks. Ref. 
C200, SYBEX $6.95 



TVT COOKBOOK 

Bk 1064 — by Don 
Lancaster. Describes 
the use of a standard 
television receiver as 
a microprocessor 
CRT terminal: Ex- 
plains and describes 
character genera- 
tion, cursor control 
and interface infor- 
mation in typical, easy 
-to- understand Lan- 
cascaster style 
$9.95 



COMPUTER 

PROGRAMMING 

HANDBOOK 

A complete guide to 
computer programm- 
ing & data process- 
ing. Includes many 
worked-out examples. 
By Peter Staak, TAB 
$9.95 



DIGITAL 
CASSETTE 

5 min. each side. Box 
of 10 $9.95. Part No. 
C-5. 




Tq QrHgf ■ Mention part no. description, and price. In USA shipping paid by us for orders accompanied by check or money order. 
1 V\fe accept COD. orders in the U. S. only, or a VISA or Master Charge no., expiration date, signature, phone no., 
shipping charges will be added. CA residents add 6.5% for tax. Outside USA add 10% for air mail postage and han- 
dling. Payment must be in U. S. dollars. Dealer inquiries invited. 24 hour order line (408) 226-4064. 



Send for FREE Catalog ... a big self-addressed envelope with 41 e postage gets it fastest! 



ELECTRONIC SYSTEMS °* b. 



P. 0. Box 21638, San Jose, CA USA 95151 



238 BYTE September 1979 



Circle 125 on inquiry card. 



PERQOM SAMPLER 



a r 





tMf 0ti 

300 ' 

j»[F30M <^l 


For your 
CIS-30+ 


SS-50 bus computer — the 



• Interface to data terminal and hvo cas- 
sette recorders with a unit only 1/10 
the size of SWTP's AC-30. 

• Select 30, 60, or 120 bytes per second 
cassette interfacing, 300, 600 or 1200 
baud data terminal interfacing. 

• Optional mod kits make CIS-30+ work 
with any microcomputer. (For MITS 
680b, ask for Tech Memo TM-CIS- 
30+— 09.) 

• KC-Standard/Bi-Phase-M (double fre- 
quency) cassette data encoding. De- 
pendable self-clocking operation. 

• Ordinary functions may be accom- 
plished with 6800 Mikbug™ monitor. 

• Prices: Kit, $79.95; Assembled, 
$99.95. 

Prices include a comprehensive instruction 
manual. Also available: Test Cassette, Re- 
mote Control Kit (for program control of 
recorders), IC Socket Kit, MITS 680b mod 
documentation, Universal Adaptor Kit 
(converts CIS-30+ tor use with any com- 
puter). MIKBUG®Motorola, Inc. 



In the Product Development 
Queue . . . 

Coming PDQ. Watch lor announce- 
ments. 

6809 Processor Card — With this SS-50 
bus PC board, you'll be able to upgrade 
with the microprocessor that Motorola 
designers describe as the "best 8-bit 
machine so far made by humans." 
The Electric Crayon™ — This color 
graphics system includes its own /nP and 
interfaces to virtually any microcomputer 
with a parallel I/O port. 

Printer Interface — For your TRS-80™. 
Interface any serial RS232 printer to your 
TRS-80™ with this system. 



'"ELECTRIC WINDOW. ELECTRIC CRAYON. Pilon- 
30 and Pilon-10 are trademarks of Percom Data 
Company, Inc. 

TRS-80 is a trademark of Tandy Corporation and Radio 
Shack which has no relationship to Percom Data Company. 

Orders may be paid by check or money order, 
or charged to Visa or Master Charge credit 
account. Texas residents must add 5% sales 
tai. 




For your data storage — Pllon-30™ and 
Pilon-10™ data cassettes 

• Orders-of-magnitude improvement in 
data integrity over ordinary audio cas- 
settes. 

• Pilon-coated pressure pad eliminates 
lint-producing felt pad of standard 
audio cassettes. 

• Smooth pilon coating minimizes erra- 
tic tape motion. 

• Foam pad spring is energy absorbing. 
Superior to leaf spring mounted pad 
which tends to oscillate and cause flut- 
ter. 

• Five-screw case design virtually pre- 
cludes deformation during assembly. 

• Price: $2.49. 




For your S-100 computer— the CI-812 

• Both cassette and data terminal inter- 
facing on one S-100 bus PC board. 

• Interfaces two recorders. Record and 
playback circuits are independent. 

• Select 30, 60, 120, or 240 bytes per 
second cassette interfacing, 110 to 
9600 baud data terminal interfacing. 

• KC-Standard/Bi-Phase-M (double fre- 
quency) encoded cassette data. De- 
pendable self-clocking operation. 

• Optional firmware (2708 EPROM) 
Operating System available. 

• Prices: kit, $99.95; assembled, 
$129.95. 

Prices include a comprehensive instruction 
manual. In addition to the EPROM Operating 
System, a Test Cassette, Remote Control Kit 
(for program control of recorders), and an IC 
Socket Kit are also available. 



CASSETTE SOFTWARE 

For 8080/Z-80 ju.C« .. . . 

BASIC ETC — Developed by the co- 
authors of the original Tiny BASIC, BASIC 
ETC is easy to use yet includes com- 
mands and functions required for power- 
ful business and scientific programs as 
well as for hobby applications. 9.5K bytes 
of RAM. 1200-baud cassette and 42-page 
user's manual $35.00 

Cassette Operating System — EPROM 
(2708) COS for the Percom CI-812 dual 
peripheral interfacing PC card . . $39.95 

If you're programming on a 6800 fiC, 
you'll want these development and de- 
bugging programs written by Ed Smith of 
the Software Works: 

Disassembler/Source Generator — Dis- 
assembles SWTP Resident Assembler, 
TSC Mnemonic Assembler/Text Editor or 
Smoke Signal Mnemonic Assembler/Text 
Editor and produces compacted source 
code suitable for re-editing. Prints or dis- 
plays full assembly-type output listing. 
4K bytes of RAM. 
(Order M68SG) $25.00 

Disassembler/Trace — Use to examine 
(or examine and execute) any area of 
RAM or ROM. "Software-single-step" 
through any program, change the con- 
tents of CPU or memory location at any 
time, trace subroutines to any depth. 
2.3K bytes of RAM. 

(Order M68DT) $20.00 

EPROM Support/Relocator Program — 
This program relocates a program in any 
contiguous area of RAM or ROM to any- 
where in RAM. Use to assemble and test 
programs in RAM, adjust programs for 
EPROM operating addresses and then 
block move to your EPROM burner ad- 
dress. 952 bytes of RAM. Loads at hex 
1000. 

(Order M68EP) $20.00 

Relocating Assembler & Linking Loader 
(M68AS) $50.00 

Relocating Disassembler & Segmented 
Source Teit Generator (M68RS) $35.00 

Americana Plus — 1 4 tunes for the New- 
tech Model 68 Music Board in machine 
language ready to load and run. Cassette 
compatible with Percom CIS-30+ and 
SWTP AC-30. Order MC-1SW . . $15.95 

HARDWARE 

Newtech Model 68 Music Board — Pro- 
duces melodies, rhythms, sound effects, 
morse code, etc. from your programs. 
Includes manual with BASIC for writing 
music scores and assembly language 
routine to play them. Installs in SWTP I/O 
slot. Assembled & tested $59.95 

The Percom ELECTRIC WINDOW™ — 

Memory-resident and programmable, 
this video display character generator 
board for your SS-50 bus displays up to 
24 80-character lines. Features dual 
character generators, dual-intensity 
high-lighting. One programmable regis- 
ter controls scrolling. Compatible with 

standard video monitors $249.95 

SS-50 Prototype Cards: 

Large card (up to 70 40-pin ICs) $24.95 

I/O size card $14.95 




PERCOM™ 'peripherals for personal computing' 



PERCOM DATA COMPANY, INC. 

DEPT. B 

211N.KIRBY* GARLAND, TX. 75042 



To order products or request additional lit- 
erature, call Percom's toll-free number: 
1-800-527-1592. For detail technical In- 
formation call (214) 272-3421. 



Circle 306 on inquiry card. 



BYTE September 1979 239 



P.O. Box 4430X Santa Clara, CA 95054 




ATTENTION ELF OWNERS 
ANNOUNCING QUEST SUPER BASIC 



At last a Full Size Basic for 1802 systems. A 
complete function Basic Including two dimen- 
sional arrays, string variables, floating point, 
arithmetic and 32 bit signed integer arithmetic 
(10 digit accuracy) with I/O routines. Easily adap- 
table on most 1802 systems. Requires 12K RAM 
minimum for Basic and user programs. Cassette 
version in stock now for Immediate delivery. 
ROM versions coming soon with exchange 
privilege allowing credit for cassette version. 
Super Basic on Cassette $40.00 



Tiny Basic Source now available $19.00 

S-100 Slot Expansion. Add 3 more S-100 slots to 
your Super Expansion Board or use as a 4 slot 
S-100 Mother Board. Board without connectors 
$9.95. 

Coming Soon: High resolution alpha/numerics 
with color graphics expandable up to 256 x 192 
resolution for less than $100. Economical ver- 
sions for other popular 1802 systems also. 
16K Dynamic RAM board expandable to 32K for 
less than $150. 



RCA Cosmac Super Elf Computer $106.95 

Compare features before you decide to buy any 
other computer. There is no other computer on 
the market today that has all the desirable bene- 
fits of the Super Elf for so little money. The Super 
Elf is a small single board computer that does 
many big things. It Is an excellent computer for 
training and for learning programming with its 
machine language and yet it is easily expanded 
with additional memory, Full Basic, ASCII 
Keyboards, video character generation, etc. 
Before you buy another small computer, see if it 
includes the following features: ROM monitor: 
State and Mode displays; Single step: Optional 
address displays: Power Supply; Audio Amplifier 
and Speaker; Fully socketed for all IC's; Real cost 
of in warranty repairs; Full documentation. 
The Super Elf includes a ROM monitor for pro- 
gram loading, editing and execution with SINGLE 
STEP for program debugging which is not In- 
cluded in others at the same price. With SINGLE 
STEP you can see the microprocessor chip opera- 
ting with the unique Quest address and data bus 
displays belore, during and after executing in- 
structions. Also, CPU mode and instruction cycle 
are decoded and displayed on 8 LED indicators. 
An RCA 1861 video graphics chip allows you to 
connect to your own TV with an Inexpensive video 
modulator to do graphics and games. There Is a 
speaker system included for writing your own 
music or using many music programs already 
written. The speaker amplifier may also be used 
to drive relays for control purposes. 



A 24 key HEX keyboard Includes 16 HEX keys 
plus load, mat, run, wait, Input, memory pro- 
tact, monitor select and single step. Large, on 
board displays provide output and optional high 
and low address. There is a 44 pin standard 
connector slot for PC cards and a 50 pin connec- 
tor slot for the Quest Super Expansion Board. 
Power supply and sockets for all IC's are in- 
cluded in the price plus a detailed 127 pg. instruc- 
tion manual which now includes over 40 pgs. of 
software info. Including a series of lessons to 
help get you started and a music program and 
graphics target game. 

Many schools and universities are using the 
Super Elf as a course of study. OEM's use It for 
training and research and development. 
Remember, other computers only offer Super Elf 
features at additional cost or not at all. Compare 
belore you buy. Super Elf Kit $105.95, High 
address option $8.95, Low address option 
$9.95. Custom Cabinet with drilled and labelled 
plexiglass front panel $24.95. Expansion Cabinet 
with room for 4 S-100 boards $41.00. NICed 
Battery Memory Saver Kit $5.95. All kits and 
options also come completely assembled and 
tested. 

Questdata, a 12 page monthly software publica- 
tion for 1802 computer users Is available by sub- 
scription for $12.00 per year. 
Tiny Basic Cassette $10.00, on ROM $38.00, 
original Elf kit board $14.95. 



Super Expansion Board with Cassette Interface $89.95 



This is truly an astounding valuel This board has 
been designed to allow you to decide how you 
want it optioned. The Super Expansion Board 
comes with 4K of low power RAM fully address- 
able anywhere In 64K with built-in memory pro- 
tect and a cassette Interlace. Provisions have 
been made for all other options on the same 
board and it fits neatly into the hardwood cabinet 
alongside the Super Ell. The board includes slots 
for up to 6K of EPROM (2708, 2758, 2716 or Tl 
2716) and is fully socketed. EPROM can be used 
tor the monitor and Tiny Basic or other purposes. 
A K Super ROM Monitor $19.95 is available as 
an on board option in 2708 EPROM which has 
been preprogrammed with a program loader/ 
editor and error checking multi file cassette 
read/write software, (relocatible cassette file) 
another exclusive from Quest. It Includes register 
save and readout, block move capability and 
video graphics driver with blinking cursor. Break 
points can be used with the register save feature 
to isolate program bugs quickly, then follow with 
single step. The Super Monitor is written with 
subroutines allowing users to take advantage of 



monitor functions simply by calling them up. 
Improvements and revisions are easily done with 
the monitor. If you have the Super Expansion 
Board and Super Monitor the monitor is up and 
running at the push of a button. 
Other on board options Include Parallel Input 
and Output Ports with lull handshake. They 
allow easy connection of an ASCII keyboard to the 
input port. RS 232 and 20 ma Current Loop for 
teletype or other device are on board and if you 
need more memory there are two S-100 slots for 
static RAM or video boards. A Godbout 8K RAM 
board is available for $135.00. Also a 1K Super 
Monitor version 2 with video driver for full capa- 
bility display with Tiny Basic and a video Interface 
board. Parallel I/O Ports $9.85, RS 232 $4.50, 
TTY 20 ma l/F $1.95, S-100 $4.50. A 50 pin 
connector sat with ribbon cable Is available at 
$12.50 for easy connection between the Super 
Ell and the Super Expansion Board. 
The Power Supply Kit for the Super Expansion 
Board is a 5 amp supply with multiple positive and 
negative voltages $29.95. Add $4.00 for shipping. 
Prepunched frame $7. 50. Case $10.00. Add $1.50 
for shipping. 



Multi-volt Computer Power Supply 

8v 5 amp, ±18v .5 amp, 5v 1.5 amp, -5v 
.5 amp, 12v .5 amp, -12 option. ±5v, ±12v 
are regulated. Kit $29.95. Kit with punched frame 
$37.45. Woodgrain case $10.00. 



60 Hz Crystal Time Base Kit $4.40 

Converts digital clocks from AC line frequency 
to crystal time base. Outstanding accuracy. Kit 
includes: PC board, IC, crystal, resistors, ca- 
pacitors and trimmer. 



TERMS: SD. 00 mm. order U.S. Funds. Calif residents add 6% tax. 
BankAmencard and Master Charge accepted. 
Shipping charges will be added on charge cards. 



Same day shipmont. First line parts only. 
Factory tested. Guaranteed money back. 
Quality IC's and other components at fac- 
tory prices. 

INTEGRATED CIRCUITS 



7IWTTI 

740QN 

740IN 

7«4N 

7409M 

7410N 

7414N 

74ZON 

7422N 

7430N 

7442N 

7445N 

7447M 

744BN 

7450N 

7474N 

7475N 

7485N 

7489N 

7490N 

7492N 

7493N 

7495N 

741 DON 

74107N 

74121N 

741 23N 

741 2 SN 

74 MSN 

74150H 

74I51N 

74154N 

741 57N 

74161N 

7416ZN 

74163N 

74174N 

741 75N 

74I90N 

74192H 

74193N 

74221 N 

7429BN 

74365N 

743GSN 

74367N 



.86 



74LSWTTL 

74LS00N .25 

74LS02H .25 

74LS04K .25 

74LS05H .25 

74LS06N 25 

74LS10N .25 

74LSI3N 40 

74LS14N 90 

74LS20N .25 

74L522N .25 

7JI.S2BM .41 

74LS30N .25 

74LS33N .39 

741S3BN .30 

74LS74N .70 

74LS75N .47 

74L59QN .51 

74LSS3N 51 

74LS95N 1 69 

74LS107N 35 

74LS112N .35 

74LS113N .35 

74LS13ZN .72 

74LS136N .35 

74LS151N .67 

74LSI55N .67 

74LS157N .67 

74LS162N Jt 

74LS163N .91 

74LS174H .95 

74LS190N 1.06 

74LS221N 1.95 

74LS25BN -87 

MLS367N 1,35 

UttEAR 

CA3045 .90 

CA3046 67 

CA3061 1.80 

CA3082 1 90 

CA30BB 2.95 
LM301 

AN/AK .35 

LM305H .87 

LM307N .35 

LM308N B9 

LM309H 115 

LM309K 1-50 

LM311H/N 90 



LM317T/K 


?m 


LM31B 


1M 


LM320K-5 


1?n 




a,m 


LM320K-12 


w\ 


LM320K-15 


1.15 


LM320T-S 


1 (Ml 


LM320TB 


i n 


LH320T-12 


IM 


LM320T-1S 


i no 


LM324N 


1,15 


LM339H 


1,55 


LM340K-5 


1.35 


LM340K-B 


1 35 


CM340K-12 


138 


LM340K-15 


135 


LM340K-24 


1.35 


LM340T-5 


1,W 


LM340T-B 


1 ?ft 


LM340T-12 


175 


LM340T-15 


175 


LM340T-1£ 


i n 


LM340T-2J 


125 


LM343H 


450 


LM350 


750 


LM370 


1.15 


LM377 


:iiio 


LM379 


100 


LM3S0N 


1.00 


IM3SI 


i m 


LM382 


t no 


LM703H 


40 


LM709H 


78 


LM723H/N 


SO 


LM733N 


87 


LM741CM 


Vt 


LM741N 


75 


LM747H/N 


.87 


LM746N 


.35 


LM1303N 


.82 


LM1304 


1,10 


LM1305 


17/ 


LM1307 


■I (ill 


L.M1310 


7 7fi 


LM145B 


47 


LM1800 


1 75 


LM1S12 


750 


LM1889 


3 00 


LM2111 


1.75 


LM29C2 


150 


LM39O0N 


Ml 




1 75 


LM3909N 


81 


MC1458V 


50 


NES40L 


?m 


NE5SON 


.65 


NE555V 


4.1 


NE556A 


.79 


NE5GSA 


1.00 


NE5B6V 


inn 


NE567V 


1,70 


NE570B 


5 00 


HE571B 


soo 


7BL05 


(Ml 


7BL08 


80 


78M05 


85 


75108 


175 


7549 1CN 


SO 




55 


7549 4CN 


.89 


Ala U 




CONVERTER 


803BB 


4fi0 


B700CJ 


13 95 


8701 CN 


V mi 


875QCJ 




L013Q 


'I'lS 


8400CJV/I 


7 40 


ICL7103 


g u 


ICL7107 


14.25 



F*K. 
CD4O00 
CD4O01 
C04002 
CD 4006 
CD40Q7 
CO 4001) 
CD4O09 
CD4O10 
CD4011 
C040I7 
CD4013 
CD4014 



CD4015 

CD401E 

CD4017 

CD401B 

CD40I9 

CO4020 

C04021 

CD4022 

CD4DZ3 

CD4074 

CO4025 

CD4026 

CD4027 

C0402B 

CD40Z9 

C04030 

CO 4035 

C04040 

CD4042 

C04043 

CD4044 

CD4046 

CD4049 

C040S0 

CD4D51 

CD40S0 

CO 4056 

CD406B 

C04069 

C04070 

CO4071 

CO4072 

CO 4073 

C04075 

CD4076 

CD4076 

CD4081 

CD4082 

CD4116 

CD4490 

CO 4507 

C0450B 

CD4510 

CD4511 

C04515 

CD4516 

C04518 

C04520 

CD4527 

CD4528 

CD4S53 

CD4566 

CD4583 

CD45B5 

CD40192 

74C00 

74C04 

74C10 

74C14 

74C2Q 

74C30 

74C48 

74C74 

74C76 

74C90 

74C93 

74C154 

74C160 

740175 

74C192 

74C221 

74C905 

74C90G 

74C914 

74C922 

74C923 

74C925 

74C926 

74C927 



8T20 
5T23 
8T24 
BT25 
8T26 
8T28 
BT97 
BT9B 




RAM 



2101-1 
2102-1 

2102AL-4 
21L02-1 
21F02 

2104A-4 
2107B-4 
2111-1 
2112-2 
2114L-3 





inns 


2513B 


R30 


MM5262 


40 


MM52BO 


300 


MM5320 


9 05 


MM5330 


SM 


PD411D-3 


400 


PD411D-4 


5 00 


P5101L 


1395 


4200A 


9 95 


82S25 


2.00 


91L02A 


1.50 


HD0165-5 


695 


MM57100 


4R0 


G 1 AY 38500- 


n»(> 


MCM657IA 


9 95 


936B 


3.50 



NB2SI36 8.75 

NB2S137 B75 

270B 10.50 

DM8577 2.90 

8223 2.90 

2716T1 29.50 

271B Intel 48.00 

CONNECTORS 

44 pin edge 2.75 
100 pin edge 4.50 
100 pin edge. WW 5.25 

IC SOCKETS 

Bolder Tin Low Profile 
PIN 1UP PIN 1UP 



18 77 36 .58 



RESISTORS V. wot 5\ 
10 per type 03 1000 per rype 01: 
25 per type 025 350 piece peck 

100 per type .015 5 per type 6.7! 



KEYBOARDS 

56 key ASCII keyboard *til 



167.50 



Fully assembled 77.50 

53 key ASCII keyboard kR 60 00 

Fully assembled 70.00 Enclosure 14 95 

uos 

Red T018 .15 

Green. Yellow T016 .20 

Jumbo Red 20 

Gieen. Orange. Yellow Jumt» 25 
Cllplfle LED Mounting Clips 87*175 
(specify red. amber, green, yellow, deai) 

CONTINENTAL SPECIALTIES In Hock 
Complete line ol breadboard lesi equip 



20 79 40 .57 MAM DO 8 dlgH Frtq. Or. 



1445 



CLOCKS 

MU5314 

MM5315 

MM5369 

MM5B41 

MM5885 

CnOOl 5.80 

CT7010 8.95 

CT7015 7.25 

HW5375AA/N 3.90 

MM5375AG/N 4.90 

7205 16.50 

7207 

720B 

7209 4.» 

OS0026CN 3 75 

050056CN 3.75 

MH53104 250 

MICnOFKOCESSOR 
68O0 1750 

6802 18.75 



15.95 



B0B5 
ZBOA 
8212 
8214 
8218 
B224 
8228 
8251 
B253 
B255 
8257 



ptae. 



13.91 



tB02DP 

plis. 17.95 

1B61P 11.50 

COP1802CD 19.95 

COP1602D 25" 
CDP1861 



6820 
6850 
6507 
6504 
6522 

UART.'FIFO 
AY5-1013 
AY5-1014 
3341 

PflOM 
1702A 

N82S23 
NS2S123 
N82S126 
N82S129 
N82S131 



12.9S 



9.95 
12.95 
12.50 
16 50 

13.60 



WIRE WRAP LEVEL 3 



16 .33 28 100 
18 57 40 1 23 



5MHi 

10 MM.' 
18 MHz 

20MH1 
32 MM 
32768 MHi 

1 B432MH2 
3.5795 MHz 
2.01DOMH1 

2 097152 MHi 
2.4576 Mm 
3.276B MHi 
5.0688 MKi 

5 165 MHz 
5.7143 MHz 
6.5536 MHi 
14.31818 MHi 
18.432 MHz 
22.11B4MHi 



KEYBOARD ENCODERS 
AY57376 $12.50 

AY5-3600 17.95 

74C922 5.50 

74C923 5 50 

HD0165-5 6.95 



D Connecton RS232 

D325P 2.95 

DB25S 3.95 

Cover 1.50 
RS232 Complete Set 6.50 

DE9S 1.95 

0A15P 2.10 

DA15S 3 10 

TRANSISTORS 

2H1893 40 

2N2222A IB 

2N2369 30 

2N2904A 70 

2N2907A .25 

2N3053 .40 

2H363B 25 

2N3643 75 

2N3904 .IS 

2N3906 IS 

2N3055 69 

2N4400 75 

2N4401 .75 

2N4402 .20 
TIP31 
TIP33A 



SPECIAL PRODUCTS 
MM586S Stopwatch Timer 9 00 
PC board 7 50 

Swttchel Mom Pushbutton 27 
3 pos lade .25 

Encoder HDQ165S 6.95 

3 Dlitl Univ. nil 
Counter Board Kit 
Operates 5-1B Voll DC lo 5 MHi 
typ- 125' LED display 10.80 

Pintronlti 1D0A Logic 
Antlyiar Kit 1224.00 

Model 10 Triggei 



if KB 



1229.00 



Model 150 Bus 

Grabber KK $369.00 

Sinciilr Jli Olgri 

MiKJmeler III 15 

Clort Calendar Ktl 123. K 

2.5 MHz FreqoencT Countir 

Kll 137.50 

30 MHr Friquency Countet 
Kll (47.76 

TRANSFORMERS 

6V 300 ma 3.25 
12 Volt 300 m* IranilOf m« 175 

12 6VCT600m» 3.75 

12V 250 ma wan plug 2.95 

12V CT 250 ma wan plug 3.50 

24V CT 400 ma 3 95 

10V 17 amp will plug 4 65 

12V 6 amp 12 95 



DISPLAY L£DS 

MAN1 CA 270 2 

MANS CC 125 

MAN72/74 CA/CA 300 1 

OL704 CC 300 1 

0L7D7(TJL707R CA 300 1 

0L727/728 CA/CC .500 1 



CA7CC 600 1 

CC BOO 1 

CC 357 

cacA 500 1 

CC/CA 500 

CC/CA BOO 2 



DL747/750 

DL750 

FND359 

FNO50O/5O7 

FND503/510 

FNO8O0/8O7 

3 ciiji: BuDOle 

4 digit Bubble 
0G8 Fluorescent 
DG10 Fluorescent 

5 digit 14 pin display 
NSN69 9 digit display 
7520 Claires photocells 
TIL311 Hex 

MA1001A 8.95 

MA1012A 8.98 

102P3 Iranerormer 27S 



Additional Drive Krt 



iy Din Kll S665 00 



Rockwell AIM 65 Computer 

6502 based single board with full ASCII keyboard 
and 20 column thermal printer. 20 char, al- 
phanumeric display, ROM monitor, fully expand- 
able. $375.00. 4K version $450.00. 4K Assem- 
bler $85.00, 8K Basic Interpreter $100.00. 
Power supply assy, in case $60.00. AIM 65 in 
thin briefcase with power supply $485.00. 



Not a Cheap Clock Kit $14.95 

Includes everything except case. 2- PC boards. 
6-.50" LED Displays. 5314 clock chip, trans- 
former, all components and full Instructions. 
Orange displays also avail. Same kit w/.80" 
displays. Red only. $21.95 Case $11.75 



Video Modular Kit $8.95 

Convert your TV set into a high quality monitor 
without affecting normal usage. Complete kit 
with full instructions. 



S-100 Computer Boards 

8K Static RAM Kit Godbout $135.00 

16K Static RAM Kit 265.00 

24K Static RAM Kit 423.00 

32K Dynamic RAM Kit 310.00 

64K Dynamic RAM Kit 470.00 

8K/16K Eprom Kit (less PROMS) $89.00 

Video Interface Kit $139.00 
Motherboard $39. Extender Board $8.99 



79 IC Update Master Manual $35.00 

Complete IC data selector, 2500 pg. master refer- 
ence guide. Over 50,000 cross references. Free 
update service through 1979. Domestic postage 
$3.50. 1978 IC Master closeout $1 9.50. No foreign 
orders. 



Auto Clock Kit $17.95 

DC clock with 4-.50" displays. Uses National 
MA-1012 module with alarm option. Includes 
light dimmer, crystal timebase PC boards. Fully 
regulated, comp. instructs. Add $3.95 for beau- 
tiful dark gray case. Best value anywhere. 



Stopwatch Kit $26.95 

Full six digit battery operated. 2-5 volts. 
3.2768 MHz crystal accuracy. Times to 59 
min. , 59 sec. , 99 1/100 sec. Times std. , split 
and Taylor. 7205 chip, all components minus 
case. Full Instructions. 



NiCad Battery Fixer/Charger Kit 

Opens shorted cells that won't hold a charge 
and then charges them up, all in one kit w/full 
parts and instructions. $7.25 



PROM Eraser 

Will erase 25 PROMs in 15 minutes. Ultra- 
violet, assembled $34.50 



Hickok 3Vz Digit LCD Multimeter 

Batt/AC oper. 0.1mv-1000v. 5 ranges. 0.5% 
accur. Resistance 6 low power ranges 0.1 
ohm-20M ohm. DC curr. .01 to 100ma. Hand 
held, W LCD displays, auto zero, polarity, over- 
range. $69.95. 



Digital Temp. Meter Kit $39.95 

Indoor and outdoor. Switches back and forth. 
Beautiful. 50" LED readouts. Nothing like it 
available, Needs no additional parts for com- 
plete, full operation. Will measure -100° to 
+ 200°F, tenths of a degree, air or liquid. 
Beautiful woodgrain case w/bezel $11.75 



FREE: Send lor your copy ol our NEW 1979 
QUEST CATALOG. Include 28c stamp. 



240 BYTE September 1979 



Circle 311 on inquiry card. 



The EXPANDORAM is available 
in versions from 16K up to 64K, so 
for a minimum investment you 
can have a memory system that 
will grow with your needs. This is 
a dynamic memory with the in- 
visable on-board refresh, and IT 
WORKS! 

• Interfaces with Altair, IMSAI, SOL-8, 
Cromenco, SBC-100, and others. 

• Bank Selectable 

• Phantom 

• Power 8VDC, ± 16VDC, 5 Watts 

• Lowest Cost Per Bit 

• Uses Popular 4116 RAMS 

• PC Board is doubled solder masked and 
has silk-screen parts layout. 



our new retail loca 



SD EXPANDORAM 

1U ttiUmatt, S-fOO THentMy 



Circle 312 or 



Extensive documentation clear- 
ly written 

Complete Kit includes all 
Sockets for 64K 
Memory access time: 375ns, 
Cycle time: 500ns. 
No wait states required. 
16K boundries and Protection 
via Dip Switches 
Designed to work with Z-80, 
8080, 8085 CPU's. 



)ISC DRIVES 





EXPAND0 64KIT(4116) 

16K $249 

32K $324 

48K $399 

64K $474 



SHUGART SA 400 5'/." 

110 KB. 35 tracks, 
SHUGART SA 400 $295.00 

SHUGART SA 400 

Willi attractive metal case with 

cutouts lor Data Cable switch. 

luse and power cord 

LOBO SA400-C $325.00 

SHUGART SA400 

with Cabinet and Power Supply. 

Assembled, tested & guaranteed 

LOBO SA400-PSC $395.00 

SHUGART 801R 8" 

6 4 megabits, single or double 

density, hard Or soft sector, writB 

protect, and more 

SHUGART 801R $449.00 

Siemens FDD 200-3 8" 
double-sided double density 

$650.00 



DISC CONTROLLER 
SD "VERSAFLOPPY" Kit 

The Versatile Floppy Disk Hnlu '1 <^Q 
Controller Y'"* ' OT 




FEATURES: IBM 3740 Soft Sectored Compati- 
ble. S-100 BUS Compatible for Z-80 or 8080. Con- 
trols up to 4 Drives {single or double sided). 
Directly controls the following drives: 

1. Shugart SA400/450 Mini Floppy 

2. Shugart SA800/850 Standard Floppy. 

3. PERSCI 70 and 277. 

4. MFE 700/750. 

5. CDC 9404/9406. 

6. GSI/Siemans FDD120-8. 

34 Pin Connector for Mini Floppy. 50 Pin Con 
nector tor Standard Floppy. Operates with 
modified CP/M operating system and C-Basic 
Compiler. The new "Versafloppy" from S.D. 
Computer Products provides complete control 
for many of the available Floppy Disk Drives. 
Both Mini and Full Size. FD1771B-1 Single Den- 
sity Controller Chip. Listings for Control Soft- 
ware are Included In price. „ . /«/*nn 

L CPM for SD Versafloppy & 1 00 



lr 



DUAL SHUGAR 
DISC DRIVES 



with"DOWf 



New from Lobo Drives, a dual Cabinet complete with"power supply; 
and Shugart 801 R disc drives. 

• Cabinet accepts 2 801 R drives mounted side by side horizontally. 

• Power Supply for 2 drives 

• Ad-on drives available 

• Assembled, tested and guaranteed by Lobo Drives. 

• Single or double density • Hard or soft sector • Write Protect 

• Capacity: Unformatted single density 3.2 megabits 
double density 6.4 i 

BM format, 2 megabits 
500 KBS transfer, 77 tracks. 

• Shugart 800 Series Compatible 

LOBO 801R-1 Pes. Dual Cabinet with 1 drive ....J. $599.00 

LOBO 801 R-2 Pes. Dual Cabinet with 2 drives $1025.00 

SHUGART 801R Ad-on disc drive $449.00 



• bing 
k»Cap 

on rV500 



ector • Write Proti 
megabits i 
megabits,^^L 

.Z\f. $59! 



r CQNriNfNTAL SPECIALTIES CORPORATION 






LOGIC PROBES 



Logic Probes and 
Digital Pulsers 



*«* "^ ^ 



CSC logic probes are (he ultimate tool for breadboard design and testing. 
These hand held units provide an Instant overview of circuit conditions. 
Simple lo use; just clip power leads to circuit's power supply, set logic 
family switch lo TTUDTL or CMOS/HTL. Touch probB to test node. Trace 
logic levels and pulses through digital circuits. Even stretch and latch for 
easy pulse detection. Instanl recognition of high, low or Invalid levels, open 
circuits and nodes. Simple, dual-level detector LEDs tell It quickly, correct- 
ly. HI (Logic "1"): LO (Logic "0"). Also Incorporates blinking pulse detector, 
e.g.. HI and LO LED3 blink on or off. tracking "1" or "0" states at square 
wave Irequencles up to 1.5 MHz. Pulse LED blinks on for V, second during 
pulse transition. Choice of three models to meet individual requirements; 
budget, project and speed ol logic circuits. 
MODEL LP-1 

Hand-held logic probe provides instant reading of logic levels for TTL, DTL. 
HTL or CMOS. Input Impadanca: 100,000 ohms. Minimum Detectable Pulie: 
50 ns. Maximum Input Signal (Frequency): 10 MHz Pulaa Detector (LED): 
High speed train or single event. Pulse Memory: Pulse or level transition 
detected and stored. -^ — 

kCSC Modal LP-1 Logic Probe-Net Each -M*9$ $42.70 




MODEL LP-2 

Economy version of Model LP-1. Safer than a vollmeter. More accurate lhan 
a scope. Input Impedance: 300,000 ohms. Minimum Detectable Pulee: 300 
ns. Maximum Input Signal (Frequency): 1.5 MHz. Pulee Detector (LED): High 
speed train or single event. Pulaa Memory: None. _^ - 

CSC Model LP-2 Logic Probe— Nel Each 04rf3f $23.70 

MODEL LP-3 

High speed logic probe. Captures pulses as short as 10 tw> Input Im- 
pedance: 500,000 ohms. Minimum Detectable Pulee: 10 ns. Maximum Input 
Signal (Frequency): 50 MHz. Pulaa Detector (LED): High speed train or 
single event. Pulae Memory: Pulse or level transition detected and stored. 
CSC Model LP-3 Logic Probe-Net Each 3fotfc$5 $66.45 



DIGITAL PULSER 

The ultimate In speed and ease of operation. Simply connect clip leads to 
.Itlve and negative power, then touch OP-1's probe to a circuit node; 
automatic polarity sensor detects circuit's high or low condition, Depress 
the pushbutton and trigger an opposite polarity pulse into the circuit. Fast 
troubleshooting includes injecting signals at key points in TTL, DTL, CMOS 
or other popular circuits. Test with single pulse or 100 pulses per second 
via built-in dual control push-button; button selects single shol or con- 
tinuous modes. LED indicator monitors operating modes by flashing once 
for single pulse or continuously tor a pulse train. Completely automatic, 
pencil-size lab/field pulse generator for any family of digital circuits. Out- 
put: Tri-state. Polarity: Pulse-sensing auto-polarity. Sync and Source: 100 
mA. Pulae Train; 100 pps. LED Indicator: Flashes for single pulse; stays lit 
for pulse train. 
CSC Model DPI Digital Pulaer-Nel Each £743$5 $71 .20 




SD COMPUTER BOARDS 



$319 KIT* 
VDB-8024 Video Display Board 
With On-Board Z80 Microprocessor 




• ['nil HIM 'hnmelcr* by U4 llnodlsjiluy 

• Ctarectcre dttplnycd by Iflflfi Revolu- 
tion 7x10 Matrix 

» Kcyhiiurd Timer iuut Interface 

• ComptaHtc Video Output 

• Separate TTL Level SpM*ronb»Uon 
urn! Vldin ( hsipulf. 

• 2K BytCH Independent (hi Board 
Memory 

• Ow-DoanJZttOMlcropnwcwtof 

• ClU'lii-WDlHoluY 



• 'M I 'jijiL-r tun) Lower CaacCharactcru 

• lYl Special ChanictcrSci 

• \SH Additional »*er Programmable 
Chafactcm 

• Full Cursor Control 

• Forward und Reverse Scrolling 
Capability 

• OjierutcsuHun Independent Term Inn! 

• Vurlnble Speed Display Rale 

• Blinking, Underlining, Field Reverse. 
Field I'niieci mid (lomtiinuUiinM 



$239 KIT' — -n-w 
SBC-100 Single Board Computer 
with Onboard RAM, PROM, CTC 




• Four Channel (.ountcr.'Tlnier 
(ZaO-CTC) 

• Software Prof) rain in utile Hand 
Generator 

• S-IOO Bus Compatible 

■ No From Panel Required (or Ope 

■ OpUnnid Vectored Iniemipt* 



• ZSOCcntnd ProccAaWg t'nit 

• l<K14ltytcs<il"Kuml<mi Access 

• HK Bytes of Available PR< >M 

• Serial Input/Outum fun « 



$249 

Z80 Starter Kit 

A Complete Microcomputer on a Board I 



Synchro 

Oiieruilori 

• I'iimiMi'I I ■ . | .. . 






Asv.H 




PRIORITY ONE ELECTRONICS 

16723B Roscoe Blvd. Sepulvedo, CA 91343 

Terms: Visa, MC, BAC, Check, Money Order, C.O.D. U.S. Funds Only. CA residents add 6% sales lax. 
Minimum order $10.00, Prepaid U.S. orders less lhan $75.00 include 5% shipping and handling, 
minimum $2.50. Excess refunded. Just in case . . . please include your phone no. 
Prices subject to change without notice. 
We will do our best to maintain prices thru Sept. 1979. OEM and Institutional 

Dhone orders welcome (213) 894-8171. (800) 423-5633 inquiries invited. 




'/.HO ('crural Processing I 


■ III Kith 


IBB 


• Twolli.dlreeUi.nulH-lili IfUltatHt? 


Instruction* 






WO) 


< )n Ikitinl Keyboard uml Display 




• SwiicliSelcciulilel'kDMiirM 


Kuiisns Cliv Stundurd Cum 


write 




Kesian 


Interlace 






• ^K line KIH'ti Minilitir In RUM 


I'ROM I'ni^runinierlliilll 


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lixpuiisiiin provtslatl lor 01 


iS-HX) 




■ fttrtu^iitneonilCliunge 


C otoieetors 






• ZHdCI'lRcKlt.terl'.-mniiiicmi.lCliiu 


Wire \Vru|i nreu liircnstini 


el mil in, 




• I piitnEViigrmiiMiuliH-Hrcukpiitiiih 


SliiHlcfiV.ilil>iH.niitiniwl 


en mil 




• Klngte'Siep Ihniugh RAM m PROM 


programming 






• Andiiit UHHCtle Ijiudiind lhiui|i 


IK Bytes nf RAM (lwqnu 


dabte ti 


«K 


• Vectored Imemipi* imwtdetl hv 


1 Ivies) 






ZHO-CTfuiidZHtM'H) 


IK Itoes ui RAM (lycpu 


ilatile u 


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• Itlcull'iirl^K-rluicntuliiiluiKl 


Bytes) 






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■iOiuimel llunlwurcCni 


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ORDER TOLL FREE 1-800-423-5633 ORDER TOLL FREE 1-800-423-5633 



Visit our new retai 



TRS-80 DISC 
DRIVE 

$ 395 




V 



Shugart SA400, housed in an attractive metal case, 
complete with power supply and termination net- 
work. All you need to do is connect the drives to your 
expansion interface. 



1410 $835°° * Separate integral 12-Key Numeric Pad 
itiw www . All 128 ASCII Codes 

• 64 Oisplayable Characters 

• 24x80 Screen Configuration 
^^^"^ TC^T * H '9 n Resolution using a 5x7 Dot Matrix 
■»— ™" mSm • TTY-Style Keyboard Layout 

• Cursor Addressing and Sensing 

• EIA Interlace 

• Eight Selectable Transmission Rates up 
to 9600 Baud 
Microprocessor Based 

• Remote Commands 

• Attractive Styling for Contemporary En- 
vironments 

Hazeltlne 1400 
same as 1410 less numeric pad 

'735 1 " 1 



HaKftnetttt 



1500 Reg. $=r*25 s 1098 00 -ah i28Asoii codes 

• 94 Displayable Characters Including 
Lower Case 

• 24x80 Screen Configuration 

• High-Resolution Characters Using a 
7x10 Dot Matrix 

1 ANSI Standard Keyboard Layout in- 
cluding Numeric Pad 

1 Cursor Addressing and Sensing 

1 Dual Intensity 

► EIA and 20MA Interface 
i • Nine Selectable Transmission Rates Up 
to 19.2 KB 

• Auxiliary EIA Output 

• Remote Editing Commands 

• Standard or Reverse Video 
!*• Microprocessor Based 



HazettW 600 



ALL THE FEATURES OF THE 
"1500" PLUS . . . 

• Cursor Control Keys 

• Protected/Unprotected Data 

> Transmit Page, Line or Batches of Infor- 
mation 

■ Function Keys— up to 127 
» Tab/Back Tab/Auto Tab 

• Format Mode with Insert and Delete 
Line Keys 

> 31 Remote Commands including "Ter- 
minal Status" 

J 510 Reg.j5J8t£ 
s 1175 



ALL THE FEATURES OF THE 
"1510" PLUS... 

Separate Microprocessor-Controlled Printer In- 
terface which allows: 

• Interfacing of both serial and parallel printers 

• Printer speed Independent of communications 
baud rate 

• Printer control codes to be sent by the CPU 
and received by the printer without restriction 
or alteration of the terminal (especially useful 
for wide carriage applications) 

' Information to be transmitted directly to either 
the printer or the terminal, or to both 

• Operating Modes/Remote Commands; 
Remote/Local Print; Printer On-Llne 

^with/without Display; Printer Off-Une 



1520 

Reg. $t660T 

s 1495 00 

PRICE DOES NOT INCLUDE SHIPPING 



• Use with TRS-80 

• Parallel interface 

• Continuous variable printing density 
80-132 characters per line 

• 5x7 dot matrix 

• Prints on plain paper, sheets, 
rolls, fan fold 

• Form thickness control 

• Horizontal and vertical 
form positioning .-"' 



CENTRONICS 779 PRINTERS 



Portable Miniscopes fori 
Electronic Professionals on 

the Go!!! The Standout 
Oscilloscope development of the I 
decade!!! Now -30MHz, dual trace] 
model. Compare the performance, 
then compare the price. 





1<t sale Probes 1$ with purchase of scope 

• 30-Megahertz bandwidth • Accuracy 3% full scale. • Internal, line or external trigger. • Bat- 
teries and charger/transformer unit included • Graticule: 4x5 divisions, each division 0.25" • 
Time base: 1 micro sec. to 0.5 sec/div 21 settings • Vertlcle Gain: 0.01 to 50 Volts/dlv. 12 set- 
tings • Size 2.9"H x 6.4"W x 8.5"D. 3.5 lbs. • TEST MOST DIGITAL LOGIC CIRCUITS IN- 
CLUDING MICROPROCESSORS •. 

41 -141 Deluxe lOtol probe with 4 interchangeable tips $27.00 

41 -37 Deluxe 10tol/1tol probe with 4 Interchangeable tips $38.50 

41 -180 leather carrying case $45.00 

MS-1 5 Single trace 15 MHz $318.00 

MS-215 Dual trace 15 MHz $435.00 



3M Scotch® Brand 
DISKETTES 



Part # 


Sides/ 
Density 


Sectoring 

8" 

Soft-IBM 
Soft-IBM 
32-Shugart 801 
32-Shugart 801 
Soft-Shugart Dbl 

5" 

Soft-Shugart SA400 
(TRS-80) 
Soft/10 SA400 
Soft/16 Micropolis 


Price 
Box of 10 


740-OP 

740/2-OP 

740-32P 

740/2-32P 

741-0 


1/single 
2/single 
1/single 
2/single 
1 /double 


$39.95 
$75.00 
$39.95 
$75.00 
$59.00 


744-OK 

744-10K 
744-1 6K 


1/single 

1/single 
1/single 


$51.00* 

$51.00* 
$51.00* 




'Price includes Kas-ette/10 Storage Box a $5.00 Value 




■'DON'T SETTLE FOR ANYTHING LESS THAN SCOTCH" 








C MODEM 


^■^^^ 




ACOUST 






NOVATION CAT 




ijytS 


• 0-300 Baud 

• Bell 103 








• Answer, Originate 



Reg. $198.00 

Sale $189.00 



NTIWN1AL SPtCtALllES 



75TOUT 



779-1 pinch roll 

friction feed 

Reg. $1250 $950°° 

779-2 tractor feet 

Reg. $1400 $1050°° 

I Call lor Discount prices on Olher Centronics Printers 




100 MHz 8-Dlglt Counter 

• 200 Hz-100 MHz Range 

• 6" LED Display 

• Crystal-controlled timebase 

• Fully Automatic 

• Portable - completely 
self contained 

• Size • 1.75" x 7.38" x 5.63" 

• Four power sources, i.e. batteries. 
1 10 or 220V with charger 1 2V with 
auto lighter adapter and external 
7.2-10V power supply. 

$4343rSale $120.00 

ACCESSORIES FOR MAX 100: 

Mobile Charter Eliminator use power 

from car battery Model 100-CLA $3.95. 

Charger/ Eliminator use 110 VAC 

Model 100 — CAI $9.95 



■'■ U. II WI ' l, ■■■■ I. I ff "". ■ ■ ' U. I M I L, 



SALE 




LOGIC MONITOR 1 

Trace signals through all types of digital circuits. Unit 
clips over any DIP IC up to 16 pins. Each of its 16 contacts 
connects to a single-bit level detector that drives a high- 
intensity, numbered LED readout activated when the ap- 
plied voltage exceeds a fixed 2 V threshold. Logic "1" 
turns LED on; logic "0" keeps LED off. A power-seeking 
gate network automatically locates supply leads and 
feeds them to the LM-1's internal circuitry. Saves minutes, 
even hours In design, troubleshooting, debugging of 
equipment. Voltage Threshold: 2 V t 0.2 V. Input Im- 
pedance: 100,000 ohms. Input Voltage Range: 4-15 V max. 
across any two or more inputs. Current Drain: 200 mA at 10 
V. Size: 4" I. x 2" w. x 1.75" d. when open. Weight: 3 ozs. 
CSC Model LM-1 Logic Monitor— Complete. 
Sale Price $54.95 



PRIORITY ONE ELECTRONICS 

16723B Roscoe Blvd. Sepulveda CA 91343 

Terms: Visa, MC, BAC, Check, Money Order, C.O.D. U.S. Funds Only. CA residents add 6% sales tax. 
Minimum order $10.00. Prepaid U.S. orders less than $75.00 include 5% shipping and handling, 
minimum $2.50. Excess refunded. Just in case . . . please include your phone no. 
Prices subject to change without notice. 
We will do our best to maintain prices thru Sept. 1979. OEM and Institutional 

phone orders welcome (213) 894-8171. (800) 423-5633 inquiries invited. 



ORDER TOLL FREE 1-800-423-5633 ORDER TOLL FREE 1-800-423-5633 




.5%, 3 1 / 2 digit 19 

Range DVM. Vt" LCD displays 

runs 200 hrs on 1 battery. 10 Meg 

Ohm Input. 1 yr. guarantee, made in 

U.S.A., test leads included. 

Available Accessories 

RC-3 1 15V AC Adapter $7.50 

CC-3 Deluxe Padded Vinyl 

Carrying Case $7.50 

VP-10 X10 DCV Probe Adapter/ 

Protector 10Kv $14.95 

VP-40 40Kv DC Probe $35.00 

CS-1 10 Amp Current Shunt $14.95 

*FREE 

Just for Asking. 
FREE BATTERY with your meter. 



• fftQftKf ftKtMM wthjounct, 
coeor loOf plittd tf.a OMOurm 
let " . t-. lor ■an 

• Soto* miu wiln MW wnaowS on 



• Mour>-inrettGiKMKiiniO0UMJctl|2 
rwrllD" l?SunHrnnlh !M(W»»Cing 
VBCIOi iu't numur Mll'2. « rnounli IGrit 
IKIcipiulinK 
ID' tiH"sion 

• rnciij-jss richf rj c*Cu>U »"0 inuiuci-oni lo> ooi.on ol 
Mini* tHi« us. or "ailing l*rm.njtiont 

> LfgtDuMl *SVmoGMDl104MPS) 

*u !".■:■ Cuntrt.»r.noijit[>«MiL i'H.'i.iMM 




1*1 SAl HOsa m<:«orisuir « tiurot' ourO 



1„ Price: 
$29.50 



RS232 & "D" TYPE CONNECTORS 

P = Plug Male S = Socket-Female C = Cover-Hood 



PART NO. 

DE-9P 

DE8S 

DE-9C 

DA15P 

DA15S 

DA1SC 

08 25P 

OB-25S 

DB51212-1 



DESCRIPTION 
9 Pm Mate 
9 Pin Female 
9 Pin Cover 
15 Pin Male 
15 Pin Female 
15 Pin Cover 
25 Pin Male 
25 Pin F»mnle 
1 pc. Grey Hood 
DB1 226-1 A 2 pc Black Hood 
D8110963-3 2 pc. Gray Hood 



PRICE 
■4 S-9 



HICKOK LX303 $74.95 



3 LEVEL GOLD WIRE WRAP SOCKETS 

Sockets purchased In multiples of 50 per type may be combined lor best price. 



11 



'n muMfrU i M'inr J 



T\ 15 

=i 1 2.2 



50 130 1.15 



DC37P 
DC37S 
DC37C 
DDSOP 
DO50S 
ODSOC 
02041 8S 



37 Pin Mai 
37 Pin Female 
37 Pm Cover 
50 Pin Male 
50 Pm Female 
50 Pin Cover 
Hardware Set (2 pa 






2.20 2.00 

3.20 3.00 

1.80 1.45 

2.M 2.50 

3.75 3.85 

1.85 1.40 

1.90 1.80 

1.80 1.55 

3.95 3 SO 

575 5.50 

2.20 1.95 

4.95 47S 

7.50 7.20 

2.50 2.20 

1.00 .80 



Connector lor CENTRONICS 700 SERIES: 
Amphenol 57-30360 lor back of Centronics 700 Series printers 
1.4-S900 5.UP-S7 50 




S10O-WWO 50/100 Conl. .125 ctrs 3 
LEVEL WIRE WRAP 025" sq. posts on 
250 spaced rows GOLD PLATED 
1-4 5-0 10-34 

1400 13 75 13.50 



DIP 



S100ALT 501100 Conl 125 ctrs 

SOLDER TAIL on .140 spaced rows 

ALTAIR motherboards GOLD Dialed 

14 5.0 10-24 

14.50 S4.25 14.00 



DIP 



S100STO 501100 Cont. . 
50LDER TAIL on 250 spaced rows loi 
VECTOR. IMSAI. CROMENCO mother 
boards GOLD plated. 

1-4 50 10-24 

S3.50 13.25 13.00 

S10OSE 501100 Com 125 ctrs PIERCED 
SOLDER EYELET tails GOLD 
1-4 5-6- 10-24 

55.00 54.50 54.00 



Other Popular Edge Connoctors 



156 ctrs PIERCED 
i. GOLD plated 
10-24 
52.20 



53.55 53.70 

IMSAI Slyle Card Guides 5/51 00 



See our July Ad for many other connectors. 



25-99 100-249 250999 




Spin 
14 pin 
16 pin 
18 pin 
20 pin 
22 pin 
24 pin 
28 pin 
40 pin 



.39 
.50 
.70 
.90 
.95 
.95 
1.25 



.36 
.38 
.42 
.60 



.85 
1.15 



.34 
.36 
.40 
.55 
.75 
.80 
.80 
1.00 



.31 
.32 
.36 
.50 
.65 
.70 
.70 
.95 




All sockets are GOLD 3 level closed entry. 2 level Tail, Low 

Profile, Tin Sockets and Dip Plugs available. CALL FOR QUOTATION 




APPLE PLUGBOARD 

Vector 4609 Peripheral Interface Plugboard (or construction of custom circuits. 
Plug compatible with Apple II. Commodore PET and Super Kim microcomputers. 
Three connectors, in addition to the standard 25/50 system bus. are available for 
input/oulput. A 20/40-contact card-edge connector, fabricated on the rear of the 
board, mates with a 3-M type ribbon connector. Alternatively, a right-angle 
solder-tail header may be positioned in this same location. The Model 4609 also 
accomodates the miniature SIP-type connectors which may be placed on the 
periphery or in mid-board. 



1-4 



5-9 



10-24 



$19.95 $17.96 $15.96 



Plugboards 





8800V 

Universal Miciocompuler/ofocessor 
plugboard, use will) S-100 bus Com- 
plete with heal sink & hardware 5.3" it 
10' x 1/16 

1-4 5-9 10-21 

S19.95 S17.95 S15.96 

8601-1 

Same as 8800V except plain less power 
Ouses & Heal sink 

1-4 5-9 10-24 

$15.22 $13.79 $12.18 



3682 9.6"x4.5" 

S10.97 

3682-2 6.5" X 4.5" 

19.81 

Hi-Density Dual-ln-Line 
Plugboard lor Wire Wrap 
wilh Power & Grd. Bus 
Epoxy Glass 1/16" 44 
pin con. spaced .156 




Phenolic 

PART NO. 
64P44XXXP 
169P44XXXP 



1M6 tfxfflt BOARD 

.042 dia holes on 

0.1 spacing for IC's 

PRICE 
SIZE 1-9 10-19 

4.5x6.5" $1.56 $1.40 
4.5x17" $3.69 $3.32 



TRS-80/APPLE 

MEMORY EXPANSION KITS 
4116's RAMS 

from Leading Manutactumrs 

<16Kx1 200ns) 



8 lor $75.00 



3677 9 6"x4.5" 

$10.90 

3677-2 6.5" X 4.5" 

$9.74 

Gen. Purpose D.I. P. 
Boards wilh Bus Patlern 
lor Solder or Wire Wrap. 
Epoxy Glass 1/16" 44 
pin ct n. s paced .156 



r r 



l 

3662 



6.5' 



r 

X 4.5' 



m 



$7.65 

3662-2 9.6" x 4.5" 

$11.45 

P pattern plugboards for 
IC's Epoxy Glass 1/16" 
44 pin con. spaced .156 



Add $3.00 for programming Jumpers 
for TRS-80 Keyboard 




IC SOCKET SALE 

14 pin Low Profile 
10/&2.10 100/$1*».00 
16 pin Low Profile 
10/$2.20 100/S16.00 
24 pin Low Profile 
3/$1.00 40/S10.00 
40 pin Solder Tail 
3/$ 1.00 40/S10.00 

24 pin Dip Plug with 

cover 

3/$1.004Q/$10.00 




3690-12 
CARD EXTENDER 
Card Extender has 100 con- 
tacts 50 per side on .125 
centers-Attached connec- 
tor-is compatible with 
S-100 Bus Systems. $25.83 
3690 6.5" 22/44 pin .156 
ctrs. Exten ders $13 .17^ 

3 

14 & 16 PIN 

GOLD 3 LEVEL 

WIRE WRAP 

SOCKES 

14 - G3 100 for 
$33.00 

16 - G3 100 for 
$33.00 
50 of each for $35.00 J 



MEMORY MEMORY 

2102LIPC Low Power 450ns in lots of 25 $1.10 
2102AL-2 Low Power 250ns in lots of 25 $1.25 
21 14-3LlKx4 300 ns Low Power 8/S50.00 

5257-3L 4Kx1 300ns Low Power 8/550.00 

2708 8K 450ns EPROM $9.00 

2716 16K 5 Volt Only EPROM $45.00 



Tg&& 



PANAVISE TILTS. TURNS, AND , 
ROTATES TO ANY POSITION. 
IT HOLDS YOUR WORK 
. EXACTLY WHERE YOU WANT IT. 



WRAP. POST 

for .042 dia. holes 
| {all boards on this page) 
IT44/C pkg. 100 . . S 2.34 
IT44/M pkg. 

1000 $14.35 

I A-13 hand installing 

toot $ 2.94 




IM-10A List $89.00 

SPECIAL 

556.95 with tube 
Perfectly balanced fluoroacont lighting 
with precision magnifier lens. Tough 
thermoplastic shade. Easy lens re- 
moval. New wire clip design permits 
easy Installation and removal of 
fluorescent tube. Comes with plastic 
shield to protect tube from soiling and 
damage. 

Colors: Gray, Black, and Chocolate Brawn. 
Comas with on* 22 watt T-S Circlln* fiuorea 
cam tub^3dloptar janjL ^ 



I ELECTRONICS 



* 



ORDER TOLL FREE 

1 80042356; 

except CA., AK., Hi., Call 
(213) 894-8171 




16723B Roscoe Blvd. Sepulveda CA 91343 

Terms: Visa, MC, BAC. Check, Money Order, CO.D. U.S. Funds Only. CA residents add 6% sales tax 
Minimum order $10.00. Prepaid U.S. orders less than $75.00 include 5% shipping and handling 
minimum $2.50. Excess refunded. Just in case . . . please include your phone no. 
Prices subject to change without notice. 
We will do our best to maintain prices thru Sept. 1979. OEM and Institutional 

hone orders welcome (213) 894-8171, (800) 423-5633 inquiries invited. 



TEST 

EQUIPMENT 

CALL FOB 

SPECIAL PRICES 



ORDER TOLL FREE 1-800-423-5633 ORDER TOLL FREE 1-800-423-5633 




Venus 2001 
Video Board 



Assembled & Tested 
$259.95 •Complete 
Unit with 4K Memory 
and Video Driver on 
Eprom assembled 
and tested $339.95 



kit 199 



95 



OPTIONAL: • Sockets $10.00 

• 2K Memory $30.00 

• 4K Memory $60.00 

• Video Driver Eprom $20.00 

• S-100 plug-in • Parallel keyboard port 

On board 4K Screen Memory (Optional). On board Eprom 
(Optional) for Video Driver or Text Editor Software. 

Up and down scrolling through video 

memory Reverse Video, Blinking Characters. 

Display : 128 ASC1 1 Characters 64 X 32 or 32 X 
16 Screen format (Jumper Selectable). 7 by 11 Dot 
Matrix Characters. 

American or European TV Compatible 

(CRT Controls Programable) Dealer Inquiries Invited 



32-K Static RAM $499. 



• S-100 Plug-In • Kit includes P.C. board, all parts 
and assembly manual • Uses 21 14L, 450 nS. 

I.C. sockets -$20.00 
P.C. BOARD BY S-100 CO. 



16-K Static RAM 249- 



• S-100 Plug-In Kit includes P.C. board, all parts and 
assembly manual. Uses2114L450 nS. 

Sockets -$10.00 
Add $40.00 for 300 nS (4MHz) RAMS 
P.C. BOARD BY WAMECO 



z-80 cpu $125. 



• S-100 Plug-In Kit includes P.C. boards, all parts 
and assembly manual. 

FEATURES: 2MHz operation • S-100 plug-in 
Power-on jump • On board provision for 2708 
(optional at $12.95). 

P.C. BOARD BY ITHACA AUDIO 



ASCII Keyboard Kit $ 79.95 




Assembled and Tested $95.95 

• Single +5V Supply • Full ASCII Set (Upper and Lower 
Case) • Parallel Output • Positive and Negetave Strobe • 
2 Key Rollover • 3 User Definable Keys • P.C. Board 
Size: 17-3/16" X 5" • Control Characters Molded on Key 
Caps • Optional Provision For Serial Output 
OPTIONAL: Metal Enclosure $27.50 • Edge Con. $2.00 • 
Sockets $4.00 • Upper Case Lock Switch $2.50 • Shift 
Register (For Serial Output) $2.00 

Dealer Inquiries Invited 

Apple II I/O Board Kit 

Plugs into Slot of Mother Board 

• 1 8 Bit Parallel Output Port (Expands to 3 Ports) • 1 Input 
Port • 15mA Output Current Sink or Source • Can be 
used for peripheral equipment such as printers, floppy 
discs, cassettes, paper tapes, etc. • 1 free software listing 
for SWTP PR40 or IBM selectric. 

PRICE: 1 Input and 1 Output Port $49.00 
1 Input and 3 Output Ports $64.00 
Dealer Inquiries Invited 



new ! A DREAM COME TRUE 



lntroducing:30 MHZ 

DUAL TRACE 
PORTABLE 
SCOPE «„_ 

for an % CCC 
amazing \_r\JiJt 

• Dual trace 2-channel; separate, 
chopped or alternate modes. • 30 megahertz 
bandwidth. • External and internal trigger. 

• Time base - 0.05 .Microseconds to 0.2 SEC/div 
21 settings • Battery or line operation. 

• Line synchronization mode. 

• Power consumption less than 50W. • Vertical gain - 
0.1 to 50 volts/div- 12 settings. • Size: 2.9" H 6.4" 

W 8.5" D. • Weighs only 3.5 lbs. with batteries. 

• Complete with input cable and rechargeable 
batteries and charger unit. 

OPTIONAL: Leather case $45.00 • 10:1 probe $27.00 
(2 for $49.00) ■■ 

MS -21 5 

15 mhz Dual Trace Portable Scope $ 399. 
MS-1515 mhz Single Trace Scope $ 299. 




MODEL 
MS 230 



SHIPPING $3.50 / California residents add 6% sales tax 

ELECTRONICS WAREHOUSE Inc 

15820 Hawthorne Boulevard 

Lawndale, CA 90260 

(213) 370-5551 



Circle 130 on inquiry card. 



Circle 1 on inquiry card. 



FRFFI UPT0S170 IN 
' *■*■*■■ MERCHANDISE 
WITH THE PURCHASE OF ONE 
OF THE FOLLOWING PET-CBM 
ITEMS!! 



ASK ABOUT 

EDUCATIONAL 

DISCOUNTS 

ON PET 




$119.00 
$ 2.25 
$ 1.60 



IEEE - RS232 Printer Adaptor for PET 
BETSI PET to S-100 Interface & Motherboard 
PET Connectors- Parallel or IEEE 

- Cassette Port 
Personal Information Management System- 
Add $3 for PET program cassette 

Protect-A-Pet dust cover 
MICROCHESS for PET (Peter Jennings) 
PET 4 Voice Music Board (MTUK-1002-2) 
Music Software (K-1002-3C) for PET 
CmC Word Processor program for PET 
Bridge Challenger program for PET 
Adventure 1 for 24K PET 
Tunnel Vision/Kat & Mouse-maze 
Graphics Utility Package for PET 
Stimulating Simulations-Book & PET tape 

Kite Fight - 2 player action game 

Write for PET Software List 
Auto-Repeat Hardware for PET 

Word Processor for PET — Machine Language 

version. Auto scroll, insert, delete, form letter append, etc. 
8K Version $ 24.00 16K or 32K with disk $ 95.00 
* Amount of Free Merchandise with Purchase of PET-CBM Item. 



PET SPECIALS ust FREE* 

PET 16N 16K full size graphics keyboard $ 995 $130 

PET 16B 16K full size business keyboard $ 995 $130 

PET 32N 32K full size graphics keyboard $1295 $170 

PET 32B 32K full size business keyboard $1295 $170 

PET 16S 16K small keyboard, integral cassette $ 995 $130 

PET32S 32K small keyboard, integral cassette $1295 $170 

PET 8K 8K small keyboard, integral cassette $ 795 $100 

PET 2040 Dual Disk Drive - 343,000 bytes $1295 $170 

PET 2040A Single Disk Drive - 171,000 bytes $ 895 $115 

PET 2022 Traclor Feed Printer $ 995 $130 

PET 2023 Pressure Feed Printer $ 849 $110 

PET C2N External Cassette Deck $ 95 $ 12 

$ 79.50 

WRITE FOR 6502 AND 
S-100 PRODUCT LIST 



KIM-1 $159 (Add $30lor Power Supply)SYM-1 

BAS-1 Microsoft ROM Basic for SYM 
Memory Plus 

SEA-16 New 16K Static RAM 
Seawell Motherboard-4K RAM 

space 
KTM-2 Synertek Keyboard and 

Video Interface with Graphics 

Capability 
RAM 16 4MHz 16K Static S-100 

2114 L 450ns 4K Static RAM 
2716 EPROM (5 Volt) 
6550 RAM (for PET 8K) 
6502 Microprocessor Chip 
6522 VIA 
6520 PIA 



$222 
$ 85 
$199 
$325 

$ 99 



1.90 

$ 9.50 

$ 17.90 

$ 49.00 

$ 19.00 

$ 25.00 

$ 13.50 

$ 7.95 

$ 7.95 

$ 13.50 

$ 13.50 

$ 7.95 

$ 24.50 ' 



FREE! 

UP TO $170 IN 
MERCHANDISE 



BOOKS 

Programming the 6502 (Zaks) 
6502 Applications Book (Zaks) 
6500 Programming Manual (MOS) 
Programming a Microcomputer:6502 
Basic for Home Computers 



$290 
$270 

$6.95 
$ 45 
$13.90 
$ 9.95 
$9.75 
$10.50 

$ 9.90 
$11.90 
$ 6.50 
$ 8.90 
$ 5.90 




3M "Scotch" 8" disks 


10/$3I 


3M "Scotch" 5" diskettes SALE 


10/J35 


Verbatim 5" diskettes 


TO/527 


(Write for quantity prices) 





Minimum Order $10.00 



A B Computers 



Cassettes (all tapes guaranteed) 

Premium quality, high output lownoise in 5 

screw housing with labels: 

C-10 10/5.95 50/25.00 100/48.00 
C-30 10/7.00 50/30.00 100/57.00 

115-A E. Stump Road 
Montgomery ville, PA 18936 
(215)699-8386 



WAMECO 

THE COMPLETE PC BOARD HOUSE 
EVERYTHING FOR THE S-100 BUSS 

* FPB-1 FRONT PANEL BOARD * EPM-2 16K or 32K BYTE EPROM 

Hex Displays, IMSAI Replaceable $54.95 2708 or 2176 interchangeable $30.00 

* FDC-1 FLOPPY DISC CONTROLLER BOARD * QMB-9 9 SLOT MOTHER BOARD 
Controls up to 8 Discs $45.00 Terminated $35.00 

*MEM-1A 8K BYTE 2102 RAM Board ....$31.95 *QMB-12 12 SLOT MOTHER BOARD 
*MEM-2 16K BYTE 2114 RAM Board ....$31.95 Terminated $40.00 

*CPU-1 8080A CPU Board * RTC REALTIME CLOCK 

With Vector Interrupt $31.95 Programmable Interrupts ., $27.95 

*EPM-1 4K BYTE 1702A EPROM $29.95 

FUTURE PRODUCTS: 80 CHARACTER VIDEO BOARD, 
IO BOARD WITH CASSETTE INTERFACE. 

DEALER INQUIRIES INVITED, UNIVERSITY DISCOUNTS AVAILABLE 

AT YOUR LOCAL DEALER 



W7J7C 



iflC. WAMECO INC. 111 GLENN WAY #8, BELMONT, CA 94002 (415)592-6141 



Circle 387 on inquiry card. 



BYTE September 1979 245 



Circle 384 on inquiry card. 



10%OFF 20 OFF 



YOUR OWN TRS-80 SYSTEM AT TREMENDOUS SAVINGS 

Centronics 730 
Same as Line Printer II 

Special 1st 25 units sold 



OTRS-80 Complete System DISK DRIVES NOW IN STOCK/ 

Includes: CPU/ Keyboard, Power Supply, 
Video Monitor, Cassette Recorder, Manual, 
and Game Cassette. 

©Line Printer 



©Mini Disk System 
OC-10 Cassettes 
©Verbatim Diskettes 



i 




REG. 
PRICE 



OUR 
PRICE 



$ 696.00 $ 557.10 



ITEM 

TRS-80 Complete System 
Level II • 4K RAM 
TRS-80 Complete System 

Level II 16 K RAM $988.00 $764.10 

Expansion Interface $ 299.00 $ 269.10 

Pertec FD200 Mini Disk Drive $ 495.00 $ 385.00 

Centronics 779 Printer $1599.00 $1175.00 

Centronics 101 Printer $1595.00 $1400 00 

Anadex DP-8000 Printer $1295.00 $995 00 

Centronics P1 Printer $ 534.00 $ 445.00 

TrendatalOOO $1495.00 $1295.00 

Memory KM16K) $ 199.00 $ 96.00 
■FREE INSTALLATION 

Verbatim Diskettes ea. $ 595 

3 $ 17.89 

10 $ 59.00 

Maxell Diskettes ea. $ 10.00 

3 $ 30.00 

10 $ 100.00 

C-10 Cassettes 5 $ 4.95 

25 $ 24.75 

12 S 29.95 
fanfold. 



C-30 Cassettes 

Paper (9V;' x 11 

3500 sheets) 

Model 

Level II— 4K 
Level II— 16K 
Expansion Interlace 



4.95 
12.00 
37 00 

7.50 
21 00 
60.00 

450 
18.75 
23 95 



$ 35.00 $ 29.95 

List Price Our Price 

$698.00 $628.20 

$988.00 $889.20 

$299.00 $269.10 



$ 850 Reg. $ 895 

Anadex 9500 

Similar to Line Printer III 

$1,295 Reg. $1,999 

* All printers include cables 

There are new developments every day — 
write or call lor the latest information. 



Outlet Hours: 



Mon.-Fri.; 9 am.- 
Sat. 12— 5 pm. 



-7 pm. 



777 Henderson Boulevard N-6 
Folcroft Industrial Park 
Folcroft PA 19032 
(215) 461-5300 



m 



TOLL FREE 

1-(800) 345-8102 'Orders only! 

FOREIGN and DOMESTIC DISTRIBUTORSHIPS AVAILABLE 



niiiitiiiiiiniiimimininiif 




BUILD YOUR OWN LOW COST 
MICRO-COMPUTER 

POWER SUPPLIES 

FOR S-100 BUS, FLOPPY DISCS, ETC. 




POWER TRANSFORMERS (with mounting brackets) 



ITEM 
NO. 



USED IN 
KIT NO. 



PRI. WINDING 
TAPS 



SECONDARY WINDING OUTPUTS 
2x8 Vac 2x14 Vac 2x24 Vac 



SIZE 
Wx D x H 



UNIT 
PRICE 



T1 
T 2 
T 3 
T 4 



0V, 110V, 120V 
0V, 110V, 120V 
0V, 110V, 120V 
0V, 110V, 120V 



2x9A 
2X12.5A 

2x9A 
2x4.5A 



2x2.5A 
2X3.5A 
2x2.5A 



2x2.5A 
2x4.5A 



3%"x3 5 /a"x3ya" 
3%"x4%"x3 1 /8" 
3%"x4Wx3 1 /b" 
3%"x3%"x3V8" 



19.95 
25.95 
27.95 
19.95 



POWER SUPPLY KITS (open frame with base plate, 3 hrs. assy, time) 

ITEM USED FOR @+8Vdc @-8Vdc @+16Vdc @-16Vdc @+28Vdc 



SIZEWxDxH UNIT PRICE 



KIT 1 18 CARDS SOURCE 18A 

KIT 2 SYSTEM SOURCE 25A 

KIT 3 DISC SYSTEM 18A 

KIT 4 DISC SOURCE 8A 



1A 
1A 



2.5A 
3A 
2A 



2.5A 
3A 
2A 



4A 
8A 



12"x6"x4%" 
12"x6"x4%" 
14"x6"x4%" 
10"x6"x4%" 



46.95 
54.95 
62.95 
44.95 



EACH KIT INCLUDES: TRANSFORMER, CAPACITORS, RESIS., BRIDGE RECTIFIERS, FUSE & HOLDER, TERMINAL BLOCK, BASE 
PLATE, MOUNTING PARTS AND INSTRUCTIONS. 

REGULATED POWER SUPPLY "R2" assy. & tested, open frame, size: 9" <w> x 5" (D) x 5" (H) $69.95 

SPECS: +5V +1%, @ 5A, +24V, +1%, @ 5A. OVERCURRENT PROTECTION AND +5% ADJ. FOR BOTH VOLTAGES. 
REMARK: IDEAL FOR ROCKWELL AIM-65 MICROCOMPUTER. ALSO -5V, @ 1A OPTIONAL, $5.00 ADDITIONAL. - 
SHIPPING FOR EACH TRANSFORMER: $4.75. FOR EACH POWER SUPPLY: $5.00 IN CALIF. $7.00 IN OTHER STATES. CALIF. RESIDENTS ADD 6% SALES TAX. OEM WELCOME. 



MAIL ORDER: 

P.O. BOX 4296 

TORRANCE, CA 90510 



SUNNY INTERNATIONAL 

(TRANSFORMERS MANUFACTURER) 
Telephone: (213) 633-8327 



STORE: 

7245 E. ALONDRA BLVD. 

PARAMOUNT, CA 90723 

STORE HOURS: 9 AM-6 PM 



246 BYTE September 1979 



Circle 354 on inquiry card. 




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16K EPROM CARD-S 100 BUSS 




OUR 

BEST 

SELLING 

KIT! 



USES 2708s! 

Thousands of personal and business systems around 
the world use this board with complete satisfaction. 
Puts 1 6K of software on line at ALL TIMES! Kit features 
a top quality soldermasked and silk-screened PC board 
and first run parts and sockets. All parts (except 2708's) 
are included. Any number of EPROM locations may be 
disabled to avoid any memory conflicts. Fully buffered 
and has WAIT STATE capabilities. 



OUR 450NS 2708'S 
ARE $8.95 EA. WITH 
PURCHASE OF KIT 



ASSEMBLED 

AND FULLY TESTED 

ADD $25 



8K LOW POWER RAM KIT-S 100 BUSS 
250 NS SALE! 

'ADD $5 
FOR 
250NS! 




$129 



KIT 



(450 NS RAMS!) 

Thousands of computer systems rely on this rugged, work 
horse, RAM board. Designed for error-free, NO HASSLE, 
systems use. 
KIT FEATURES: 
1 



Doubled sided PC Board with solder 
mask and silk screen layout. Gold 
plated contact fingers. 

2. All sockets included. 

3. Fully buffered on all address and data 
lines. 

4. Phantom is jumper selectable to pin 
67. 

5. FOUR 7805 regulators are provided 
v on card. 



Blank PC Board w/Documentation 
$29.95 

Low Profile Socket Set. ..13.50 
Support ICs (TTL & Regulators) 

$9.75 

Bypass CAP'S (Disc & Tantalums) 

$4.50 

ASSEMBLED AND FULLY 
BURNED IN ADD $30 , 



16K STATIC RAM KIT-S 100 BUSS 



\r 



$ 279 



KIT 



PRICE CUT! 

FULLY 

STATIC, AT 

DYNAMIC PRICES 



.11 I I I I 1 I I I I I I I I I I 
1....... ..■.■■!■■ 



VJUkk 



WHY THE 2114 RAM CHIP? 

We (eel Ihe2114willbethenexi industry standard 
RAM chip (like the 2102 was} This means price. 
availability, and quality will all be good! Next, the 
2114 is FULLY STATIC We feel this is the ONLY 
way to go on the S-100 Buss' We've all heard the 
HORROR siones about some Dynamic Ram 
Boards having trouble with DMA and FLOPPY 
DISC DRIVES Who needs these kinds ot 
problems 7 And finally, even among other 4K 
Static RAM's the 21 14 stands out r Not all 4K static 
Rams are created equal! Some of the other 4K's 
have clocked chip enable lines and various timing 
windows fuil m critical as Dynamic RAM's Some 
of our competitor's 16K boards use these "tricky" 
devices But not us! The 21 14 is the ONLY logical 
choice for a irouble-tree. straightforward design. 



KIT FEATURES: 

1. Addressable as four separate 4K Blocks. 

2. ON BOARD BANK SELECT circuitry. 
(Cromemco Standard!) Allows up to 512K on 
line! 

3. Uses 21 14 (450NS) 4K Static Rams 

A ON BOARD SELECTABLE WAIT STATES 
5 Double sided PC Board, with solder mask and 
silk screened layout. Gold plated contact fingers 

6. All address and data lines fully buffered 

7. Kit includes ALL parts and sockets. 

8. PHANTOM is jumpered to PIN 67 

9. LOW POWER under 2 amps TYPICAL from the 
■*6 Volt Buss. 

10. Blank PC Board can be populated as any 
multiple of 4K. 



BLANK PC BOARD W/DATA— $33 
LOW PROFILE SOCKET SET-$12 ASSEMBLED & TESTED-ADD $30 
SUPPORT ICS & CAPS-$19.9S 2114 RAM'S-8 FOR $69.95 J 



16K STATIC RAM SS-50 BUSS 



s 295 



KIT 



FULLY STATIC 
AT DYNAMIC PRICES 



KIT FEATURES: 




FOR SWTPC 
6800 BUSS! 



ASSEMBLED AND 
TESTED - $30 



1. Addressable on 16K Boundaries 

2. Uses 2114 Static Ram 

3. Runs at Full Speed 

4. Double sided PC Board. Solder 
mask and silk screened layout. 
Gold fingers. 

5. All Parts and Sockets included 

6. Low Power: Under 2 Amps 
Typical 



BLANK PC BOARD— S33 



COMPLETE SOCKET SET— S12 



SUPPORT ICS AND CAPS-S19.95 



NEW! G.I. COMPUTER SOUND CHIP 

AY3-8910. As featured in July. 1979 BYTE! A fantastically 
powerful Sound & Music Generator. Perfect for use with any 8 Bit 
Microprocessor. Contains: 3 Tone Channel, Noise Generator, 3 
Channels of Amplitude Control, 16 Bit Envelope Period Control, 
2-8 Bit Parallel I/O. 3 D to A Converters, plus much more! All in 
one 40 Pin DIP. Super easy to interface to the S-100 or other 
busses. 
SPECIAL OFFER: $14.95 each Add $3 for 64 page Data Manual. 

Initial slock very limited FIRST COME FIRST = EFIVED' 



Z-80 PROGRAMMING MANUAL 

By MOSTEK, or ZILOG. The most detailed explanation 
ever on the working of the Z-80 CPU CHIPS. At least 
one full page on each of the 158 Z-80 instructions. A 
MUST reference manual for any user of the Z-80. 300 
pages. Just off the press. $12.95 



PROC. TECH. QUITS THE MICROPROCESSOR BUSINESS! 

FACTORY CLOSE OUT - SPECIAL PURCHASE! 

#16KRA 

16K S-100 Dynamic Ram Board - $149. 95 

ORIGINALLY PRICED AT $429 each! 

We purchased the remaining inventory of PT's popular 
16K Ram Board when they recently closed their plant. 
Don't miss the boat! These are brand new, fully tested, 
ASSEMBLED and ready to go. All are sold with our 
standard 90 day limited warranty!! 

72 Page Full Manual, Included Free! 



NOT ASSOCIATED WITH DIGITAL RESEARCH OF CALIFORNIA. THE SUPPLIERS OF CPM SOFTWARE. 



Erf Digital Research: Computers 

••;::: a <of texas> 

•••••A P.O. Box 401565 



GARLAND, TEXAS 75040 • (214) 271-2461 



TERMS: Add soc postafic w pny hulanri' Oidetsiinilpi 
NnCOH Wo arropt Visn MastcrCh.iitiP and Anioi.cn 
Res add 5", Tax Fntpipn ni dpi r (oxcrpt Canada add ^O" 
Rack Guarantor 1 on alt Moms 



:if. add 75C handling 
i Expross raid? Tpx 
P&H SWPnvMowv 




;>:. 

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Circle 100 on inquiry card. 



BYTE September 1979 247 




Computer Products 



i 



The €xicly 
SORC6R6R 



Flenbilty is the key. The Sorcerer Computer gives you the flexibility of using ready-to- 
run, pre-packaged programs or doing your own thing and personalizing the programs for 
yourself. Which ever you choose, the Sorcerer is the personal computer that speaks your 
language. 

The Sorcerer also provides full graphics capabilties. Each character, formed by an 8 i 8 

dot cell, can be programmed as a graphic symbol set. High resolution (512 x 240 

addressable points) gives a total of 122.880 locations tor super animation and extremely 

tight plotting curves. The alphanumeric set gives 64 x 30 characters on the video screen 

PART NUMBER: SYO-S016A 

With 16K of memory $1150.00 

i mmmmmmmtmmmmmmmm I 



Rockwell Aim-65: The Head-Stan 
in microcomputers 

RKIM-1 compotible machine with 
on-board printer and o real key- 
boardl 

1375.00 ui/IK ARM 

MSO.00 w/4K RRM 
4K assembler/editor in ROM $80 
8H BASIC in ROM: $ 100.00 

Power Supply $59.95 

Case of RIM-65 $49.95 

Special Package Price: $599:00 

AIM-65 I4K), Power SuoplV. Case, and 8K BASIC ROM 




NOVATION iCAT RCOUSTic modgm 

^■^ Features Include: 300 Baud 
onnn fi nsuj er/Originote. S e " ' 03. Comes 
SI 89.00 Assembled ond Tested 



PROTO BOARD 

Includes gold plated 
fingers. S-100 size, holds 
72-16 pin dips, accomo- 
dates all 8 thru 40 pin dip 
packages. 

Reg -S19 9S Special Prlce- 
$16.95 pART TSX-140B 



SD SYSTEMS 
SBC-100 

An S-100 single Doard com 
puler Z-80 CPU wilh 1024 
bylesolRAM 8lo32K bytes 
ol PROM Sertal I O porl 
Kit $239.95 

fesserribjed $369.95 



SD SYSTEMS 
Z-80 STARTER KIT 

Baied on the powerful Z80 
CPU, this hit is an ideal 
Introduction to micropro- 
cessors, II has an on-board 
keyboard and display, plus 



cassette tape Interface and 
expansion provisions tor 
two S-100 connectors. This 
"Do-it-ail" Board will also 
program the 2716 2K 
EPROM 

Kit $249.95 

Assmbld and Tstd $399 95 



TEXTOOLZIP DIP* II 



men. Sockets 

16 pin Zip Dip II S5.50 



24 pin Zip Dip II 
40 pm Zip Dip II 



$7.50 
$10.25 



INSERTION FORCE 



LEEDEX MONITOR 

• 12" Black ond While 

• 12MHZ Bandwidth 

• Handsome Plastic Case 



$139. 



rRSaO 1 APPLE 'SORCERER'TRS-BO'APPL 

JADE MEMORY 
EXPANSION KITS For 
TRS-80. Apple. & Exidy 
4116'i 

Everything a person needs to 
add 16K ol memory. Chips 
come neatly packaged with 
easy to follow directions. In 
minutes your machine is 
ready for games and more 
advanced software. 

$82.00 



HIGH QUALITY 13 INCH COLOR 
MONITOR!— Specially matched lor 
use with the TI-99/4 console. Uses a 
simple, sure hook-up. 
UP TO 72K TOTAL MEMORY 
CAPACTIY— 16K RAM, plus up to 
26K ROM onboard, plus up to 30K 
ROM In Tl's Solid State Software 
Command Modules. 
16-COLOR GRAPHICS CAPABIL- 
ITY- Easy to access high resolution 
graphics have special features that 
let you define your own characters, 
create animated displays, charts, 
graphs, etc. 

MUSIC AND SOUND EFFECTS— 
Provides outstanding audio 
capability. Build three-note chords 
and adjust frequency, duration and 
volume quickly and simply. You can 
build notes with short, straightfor- 
ward commands. Five full octaves 
from 110 Hz to beyond 40,000 Hz. 
BUILT-IN EQUATION CALCULA- 
TOR— Unique convenience feature 
helps you find quick Solutions to 
everyday math problems, as well as 
complex scientific calculations. 



TSCFIS INSTRUMENTS 

TI-99/4 




HOM€ 
CO/WUT6H 



F€flTUR€S INCWD€ R COLOR MONITOR, 
1 6H RRM M6MORV, SRSIC BUILT INTO TH6 
CONSOie. RND TUJO COMPRCHCNSIVe MAN- 
UALS €ASV FOR THE Q6GINN6R - CHaieNG- 
ING FOR THe OPCRT. 

Programs are sealed securely in SOLID STATE 
SOFTWARE COMMAND MODULES. These ROM 
packs actually add memory to the TI-99/4 so that the 
console's memory can be utilized (or user input. 

The software applications are presently broken down 
into lour areas: 1) Home Management/Personal 
Finance. 2) Education. 3) Entertainment. 4) BASIC. 

SVO-8994R $1150.00 



JADE SERIAL/PARALLEL I/O BOARD 

Features Include: S-100 Compatible ■ Two serial I/O Pons using 
software- programmable UARTS ■ One general purpose latched parallel 
I/O Port Ideal for printer Interlace or control ■ Switch selectable ■ On 
board "Kansas City" standard cassette Interface useable upto 1200 Baud, 
allowing storage of up to 180,000 bytes on a 30 minute audio cassette. 
Assembled and Tested Kit 

IOI-1040A, $179.95 IOM040K $124.95 

Bare Board with Manual IQM040B $30.00 



SVM-l 

Port Number:CPK-5002A 



$245 



6502- BASED SINGLE BOARD COMPUTER WITH 
KEYBOARD/DISPLAY, KIM-1 HARDWARE 
COMPATIBLE. COMPLETE DOCUMENTATION. 

SVM-l CAS6. C-NX-000005 $39.95 



THE BIG Z 



THE NEW Z-80 
CPU BOARD FROM JADE 

Features Include: ■ S-100 Compatible, available in 2MHz or 4MHz 
versions. ■ Onboard 2708. 2716. 2516. or 2532 EPROM can be 
addressed on any 1K. 2K. or 4K boundary, with power-on jump to 
EPROM. ■ Onboard EPROM may be used in SHADOW mode, 
allowing lull 64K RAM to be used. ■ Automatic MWRITE generation 
it Iron! panel is not used. ■ On-board USART for synchronous or 
asynchronous RS232 operation (onboard baud rate generator). ■ 
Reverse-channel capability on USART allows use with buffered 
peripherals or devices with "not-ready" signal. 

2MHz- BARE BOARD 4 MHz- 

tmru CPU-302O0B....S40.00 

KifCPU-30200K. 2 lbs $149.95 Kit: CPU-30201K, 2 lbs $159.95 

Assembled and Tested: Assembled and Tested 

CPU-30200A. 2 lbs $199.95 CPU-30201A. 2 lbs S209.95 



- 



GRI KEYBOARDS 

Features Include: Full 128 character ASCII ■ 
Trl-Mode Mos encoding ■ MOS/DTL/TTL 
compatible output ■ Two-key rollover ■ Level 
and pulse strobe ■ Shift and alpha lock ■ 
Selectable parity ■ Positive or Negative Logic 
■ All new OEM grade components ■ Gold 
contact, low bounce keyswithces ■ Rugged G- 
10 printed circuit board ■ Custom 2 shot 
molded keycaps ■ Low power consumption ■ 
Optional numeric pad available ■ Custom 
enclosures available. 
Model 756A 

Assembled- KBA-30756A $79.95 

Model 753K (53 Key, Teletype Keyboard with 
lower case) 

Kit- KBA-30753K $65.95 



DB25-CONNECTORS 

DB25P- CND1251 $2.25 

DB25S- CND1252 $3.25 

DB25C- CND1253 (Cover) $1.50 

RS232 Special: DB25P, DB25S, plus Hood 
only $6.50 (Pari Number: CND-1250) 



MICROPROCESSORS 

F80 $16.95 

280 <2MHz) $10.95 

Z80A(4MHz) $14.95 

CDP1802CD $19.95 

6502 $11.95 

6800 $9.75 

6802 $14.00 

S008-1 $15.95 

8035 $24.00 

8035-8 $24.00 

8080-A $10.00 

8085 $23.00 

TMS9900TL $49.95 

8080A SUPPORT DEVICES 

8212 $2.90 

8214 $4.65 

8216 $2.75 

8224 (2MHz) $4.30 

8226 $2.75 

8228 $6.40 

8238 $6.40 

8243 $8.00 

8251 $7.50 

8253 $20.00 

8255 $6.40 

8257 $18.00 

8259 $18.00 

8275 $51.20 

8279 $17.70 

USRT 

S2350 $10.95 

UARTS 

AV5-1013A $5.25 

AY5-1014A $8.25 

TR1602B $5.25 

TMS6011 $5.95 

6800 PRODUCT 

6821P $5.25 

6828P $9.50 

6834P $16.95 

6850P $4.80 

6B52P $5.25 

6860P $9.25 

6862P $12.00 

6875L $7.30 

6880P $2.50 

CHARACTER GENERATORS 

2513 Upper (1-12+5) $6.75 

2513 Lower (1-12+5) $6.75 

2513 Upper (5 volt) $9.75 

2513 Lower (5 volt) $10.95 

PROMS 

1702A $5.00 

2708 $9.95 

2716 $49.95 

2716 (5v) $49.95 

2758 (5v) $30.00 

DYNAMIC RAMS 

4115 $5.00 

416D/4116 (200m) $12.50 

2104/4096 $4.00 

2107B-4 $3.95 

TMS4027/4096 $4.00 



STATIC RAMS 
2114 (450ns) 
2114 (300ns) 
TMS4044/ 

MM5257(4S0m) $8.00 
TMS4044/ 

MM52S7(300m) $9.95 
21L02 (450m) 
21L02 (250ns) 
4200A (2O0m) 
410D (200n>) 



1—15 
$8.00 
$9.00 



$1.50 
$1.75 
$9.95 
$8.25 



16—100 

$6.95 

$8.00 

$7.50 

$8.75 
$1.20 
$1.50 
$8.50 
$7.00 



248 BYTE September 1979 



Circle 195 on inquiry card. 



£ 



PfilCeS GOOD IN TH€ UN[T€D SW€S AND CANADA 

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